Opinion by Judge THOMAS; Dissent by Judge O’SCANNLAIN.
ORDER
In response to the petition for rehearing, the panel has elected to file an amended opinion and amended dissent. The amended opinion and dissent are filed concomitantly herewith. With the filing of the amended opinion and dissent, Judges Schroeder and Thomas voted to deny the petition for rehearing and rehearing en banc. Judge O’Scannlain voted to grant the petition for rehearing and rehearing en banc.
The full court was advised of the petition for rehearing en banc. A judge requested a vote on whether to rehear the matter en banc. The matter failed to receive a majority of the votes of the nonrecused active judges in favor of en banc consideration. Fed. R.App. P. 35.
The petition for rehearing and rehearing en banc is DENIED. The Court will en*941tertain a further petition for rehearing and rehearing en banc as to the amendments made to the opinion. See Ninth Circuit General Order 5.3(a).
All pending motions are DENIED.
Judge CALLAHAN’S dissent from rehearing en banc follows.
OPINION
THOMAS, Circuit Judge:Michael Emerson Correll, an Arizona inmate sentenced to death, appeals the district court’s denial of his petition for writ of habeas corpus following our remand for an evidentiary hearing. We reverse.
I
This capital case arises under a federal habeas corpus provisions that have been supplanted by the Antiterrorism and Effective Death Penalty Act of 1996, Pub.L. No. 104-132, 110 Stat. 1214 (“AEDPA”), and a state capital sentencing statute that has since been repealed.
The factual history of this case was detailed in our earlier opinion, Correll v. Stewart, 137 F.3d 1404, 1408-10 (9th Cir. 1998) (“Correll I”). Briefly, Correll was convicted by an Arizona jury in 1984 of first degree murder, attempted first degree murder, kidnapping, armed robbery, and first degree burglary, all for his role in a triple homicide. Id. at 1408. He was sentenced to death by the trial judge, id. at 1410, and the Arizona Supreme Court upheld his conviction, State v. Correll, 148 Ariz. 468, 715 P.2d 721 (1986). The Supreme Court, however, modified his death sentence as to one of the victims and invalidated one aggravating factor. Id. at 730-31; 734-35.
In 1987, Correll timely filed a petition for post-conviction relief pursuant to Arizona Rule of Criminal Procedure 32. In this petition, Correll asserted multiple violations of his constitutional rights, including his right to the effective assistance of counsel during the guilt and penalty phases of his trial, his right to confrontation, and his right to reliability in capital sentencing. Correll later filed five supplements to his petition, adducing evidence of his mental impairment and his attorney’s ineffectiveness. The Arizona trial court summarily dismissed Correll’s petition and subsequently denied Correll’s motion for rehearing. The Arizona Supreme Court denied review without comment.
Correll subsequently filed a petition for writ of habeas corpus in federal district court under 28 U.S.C. § 2254. Correll alleged fifty-three constitutional violations at trial, at sentencing, and during the appellate process. The district court determined that twenty-six of Correll’s claims were procedurally barred, then granted summary judgment against Correll on his remaining constitutional claims.
On appeal, we affirmed all of the district court’s order except as to Correll’s contention that he was entitled to an evidentiary hearing on his claim of ineffective assistance of counsel at sentencing. Correll I, 137 F.3d at 1420. We remanded that issue to the district court with instructions to hold an evidentiary hearing. Id.
On remand, the district court conducted a nine day evidentiary hearing. Applying the standards set forth in Strickland v. Washington, 466 U.S. 668, 104 S.Ct. 2052, 80 L.Ed.2d 674 (1984), and its progeny, the district court concluded that the performance of Correll’s attorney at sentencing was deficient but that Correll had suffered no prejudice. The district court therefore granted judgment against Correll on his federal habeas corpus petition. This timely appeal followed.
Because Correll’s petition for a writ of habeas corpus was filed before the effective date of AEDPA, pre-AEDPA law gov*942erns our consideration of the merits. Lindh v. Murphy, 521 U.S. 320, 327, 117 S.Ct. 2059, 138 L.Ed.2d 481 (1997); Jeffries v. Wood, 114 F.3d 1484, 1494 (9th Cir.1997) (en banc). Under pre-AEDPA law, we consider a claim alleging ineffective assistance of counsel as a mixed question of law and fact, which we review de novo. Rios v. Rocha, 299 F.3d 796, 799 n. 4 (9th Cir.2002). We review the district court’s denial of Correll’s habeas petition de novo and the district court’s factual findings for clear error. Id.
II
As the Supreme Court has long instructed, the Sixth Amendment right to counsel in a criminal trial includes “the right to the effective assistance of counsel.” McMann v. Richardson, 397 U.S. 759, 771 n. 14, 90 S.Ct. 1441, 25 L.Ed.2d 763 (1970). This right extends to “all critical stages of the criminal process,” Iowa v. Tovar, 541 U.S. 77, 80-81, 124 S.Ct. 1379, 158 L.Ed.2d 209 (2004), including capital sentencing, Silva v. Woodford, 279 F.3d 825, 836 (9th Cir.2002). “Because of the potential consequences of deficient performance during capital sentencing, we must be sure not to apply a more lenient standard of performance to the sentencing phase than we apply to the guilt phase of trial.” Mak v. Blodgett, 970 F.2d 614, 619 (9th Cir.1992).
Under the familiar Strickland standard, to prevail on his claim of ineffective assistance of counsel during the penalty phase of his trial, Correll must demonstrate first that the performance of his counsel fell below an objective standard of reasonableness at sentencing and, second, that “there is a reasonable probability that, but for counsel’s unprofessional errors, the result of the proceeding would have been different.” 466 U.S. at 694, 104 S.Ct. 2052. Under Strickland, we measure an attorney’s performance against an “objective standard of reasonableness,” calibrated by “prevailing professional norms.” Id. at 688,104 S.Ct. 2052.
There are two aspects of Correll’s penalty phase defense that are at issue in this appeal: the investigation of possible defenses and the presentation of valid ones.
A
Counsel has a duty at penalty phase “to conduct a thorough investigation of the defendant’s background.” Williams v. Taylor, 529 U.S. 362, 396, 120 S.Ct. 1495, 146 L.Ed.2d 389 (2000). “To perform effectively in the penalty phase of a capital case, counsel must conduct sufficient investigation and engage in sufficient preparation to be able to ‘present[] and explain! ] the significance of all the available [mitigating] evidence.’ ” Mayfield v. Woodford, 270 F.3d 915, 927 (9th Cir.2001) (en banc) (quoting Williams, 529 U.S. at 399, 120 S.Ct. 1495) (alterations in original). When it comes to the penalty phase of a capital trial, “[i]t is imperative that all relevant mitigating information be unearthed for consideration.” Caro v. Calderon, 165 F.3d 1223, 1227 (9th Cir.1999), as amended.
The ABA Standards for Criminal Justice provide guidance as to the obligations of criminal defense attorneys in conducting an investigation. Rompilla v. Beard, 545 U.S. 374, 387, 125 S.Ct. 2456, 2466, 162 L.Ed.2d 360 (2005); Williams, 529 U.S. at 396, 120 S.Ct. 1495. The standards in effect at the time of Correll’s capital trial clearly described the criminal defense lawyer’s duty to investigate, providing specifically:
It is the duty of the lawyer to conduct a prompt investigation of the circumstances of the case and to explore all avenues leading to facts relevant to the merits of the case and the penalty in the event of conviction. The investigation should always include efforts to secure *943information in the possession of the prosecution and law enforcement authorities. The duty to investigate exists regardless of the accused’s admissions or statements to the lawyer of facts constituting guilt or the accused’s stated desire to plead guilty.
ABA Standards for Criminal Justice 4-4.1 (2d ed. 1982 Supp.).
As measured against these prevailing professional norms, there can be little doubt that Correll’s penalty phase counsel fell below an objective standard of reasonableness.
First, Correll’s attorney did little to counsel Correll about potential mitigating arguments, even though “[ajdequate consultation between attorney and client is an essential element of competent representation of a criminal defendant.” United States v. Tucker, 716 F.2d 576, 581 (9th Cir.1983) (citation omitted). Correll alleges that defense counsel met with him only once, for five minutes, between trial and sentencing. Correll I, 137 F.3d at 1412. At the evidentiary hearing, his attorney contradicted that allegation, testifying that he met with Correll “[pjrobably two or three times.” Based on the attorney’s testimony, the district court rejected Correll’s assertion of minimal consultation, specifically finding that Correll’s attorney “did maintain regular contact with Petitioner prior to sentencing.”
The record, however, reveals that the district court’s finding of adequate consultation was clearly erroneous. Even if counsel’s efforts to communicate with Cor-rell exceeded one five-minute meeting, his penalty phase consultation was unreasonably limited. Indeed, Correll’s attorney was not even confident that he had met with Correll more than once; he testified, “I know definitely one time that I can recall, but I think probably two or three times.” His hand-written notes from the time period confirm only two meetings. More importantly, the attorney’s notes make clear that Correll failed to grasp the significance of the sentencing hearing and that his attorney made, at best, minimal efforts to explain it to him. In fact, Cor-rell asked to be sentenced as soon as possible so that he could go to the Department of Corrections in time to pick up a Christmas package, and his attorney acquiesced in that request. At no point did Correll’s counsel explain to Correll the possibility of a mitigation defense arising from Correll’s drug use, brain damage, family history, or psychiatric record, and at no point did counsel ask Correll for information or contacts specifically related to those issues. We therefore conclude that the district court’s factual finding on this issue was clearly erroneous and that the district court’s legal conclusion was in error. Cor-rell’s attorney did not maintain constitutionally adequate contact or engage in constitutionally adequate consultation with Correll in between conviction and sentencing.
Second, penalty phase investigations in capital cases should include inquiries into social background, including investigation of any family abuse, mental impairment, physical health history, and substance abuse history. Summerlin v. Schriro, 427 F.3d 623, 630 (9th Cir.2005) (en banc). That investigation should include examination of mental and physical health records, school records, and criminal records. Id. “Defense counsel should also personally review all evidence that the prosecution plans to introduce in the penalty phase proceedings, including the records pertaining to criminal history and prior convictions.” Id. (citing Rompilla, 125 S.Ct. at 2465). In this case, although defense counsel was aware that potential mitigating evidence existed, he did not explore any avenues that might lead to development of that evidence.
*944The district court excused defense counsel’s failure to investigate many of these mitigating factors on the ground that Cor-rell “had not informed” his attorney of the various “allegations” that amounted to classic mitigating circumstances. On that basis, the district court apparently concluded that defense counsel was unaware of — and could not investigate — many of the mitigating factors that Correll proffered during the evidentiary hearing. Although the district court was apparently right to conclude that Correll did not specifically inform his counsel of some mitigating factors, the court’s implicit conclusion that the attorney was ignorant of those factors is clearly erroneous. When questioned during the mitigation hearing, Correll’s trial counsel explicitly confirmed that he was aware of Correll’s mental health disorders, psychiatric commitments, drug abuse history, brain injury, and family dysfunction. Defense counsel testified as follows:
Q. Were you aware that [Correll] had spent nearly his entire teen life, from ages 14 to 18, as a ward of the State of California and an inmate of the California Youth Authority?
A. Yes.
Q. [T]hese [referring to exhibit] are notes from your first interview and your first meeting with Mr. Correll?
A. Yes.
Q. And you see there noted, don’t you, that you learned of mental disorders. You checked the mental disorders box, and that he had been committed twice, and “in joint.” Do you see that?
A. Yes.
Q. So you knew from the inception of this case that Mr. Correll had a couple of commitments to psychiatric or mental institutions?
[Objection colloquy omitted.]
THE WITNESS: Yes, I definitely knew that.
[Colloquy omitted.]
Q. You also learned, during the course of your representation of Mr. Cor-rell, that he had a rather lengthy drug abuse history, didn’t you?
A. Yes.
Q. Did you also learn, during the course of your representation, that other of the Correll brothers had criminal records and themselves had been incarcerated in the Youth Authority?
A. Yes.
Q. Did you learn that his sister Robin was residing in a foster home?
A. I believe I was aware of that. I don’t recall at this point.
Q. Did you then, conclude that there were problems of some description within the Correll household that may have contributed to the Correll childrens’ [sic] poor record of success?
A. Oh, it was obviously an extremely dysfunctional family.
This testimony makes perfectly clear that Correll’s trial counsel was aware of many if not all relevant mitigating factors. The district court’s implicit conclusion to the contrary was clearly erroneous.
Indeed, in light of the abundance of classic mitigation evidence of which counsel was aware, his almost complete failure to investigate is startling. Despite his knowledge that Correll was a drug user with an extremely troubled childhood, defense counsel did not interview witnesses about these issues or obtain records concerning these matters. The district court found that Correll’s attorney “interviewed or tried to interview” about forty or fifty witnesses but that “[t]he witnesses were not able to provide relevant useful mitiga*945tion information.” On that basis, the district court found that counsel’s investigative efforts, at least with respect to the interviews, were adequate. Once again, the district court’s factual finding and legal conclusion are clearly erroneous.
Admittedly, counsel did meet with some witnesses during the trial phase, including those members of Correll’s family who would cooperate. But counsel testified that he met only once with Correll’s father, sister, and brother, “around the kitchen table at the same time,” and probably spent only “[a] couple hours” with them. Furthermore, Correll’s counsel admitted that he interviewed witnesses only during the guilt phase, not during the sentencing phase. Although the attorney testified that he was looking for mitigation information as well as exculpatory information during those pre-trial interviews, he failed to ask any direct questions or to conduct any direct investigation related to the mitigating factors that are now at issue. When counsel was asked at the evidentiary hearing whether he had questioned the interviewees about Correll’s drug abuse, head injury, psychiatric history, or family dysfunction, counsel testified that he asked no such specific questions but, rather, asked the interviewees simply to “tell [him] anything [they could] tell [him] that would help.” As a result, counsel’s interviews were substantively worthless. Thus, his failure to gather mitigating information did not result from its unavailability; it resulted from counsel’s complete failure to ask any relevant questions. The district court’s conclusion to the contrary was clearly erroneous.
Additionally, trial counsel did not obtain records from Correll’s schools or from psychiatric institutions, even though counsel admitted that those records may have contained mitigating evidence. Counsel also failed to obtain police reports on prior convictions and records regarding the time that Correll was in the custody of the California Youth Authority. Counsel did not obtain Correll’s medical records, and he made no inquiry into whether an X-ray or other diagnostic test was performed to determine whether Correll suffered any brain injury following an incident in which a wall fell on Correll’s head.
During the evidentiary hearing, counsel could not recall what efforts he made to gather Correll’s psychiatric records, though he did remember that he failed to obtain records from Correll’s stays at various mental health centers.1 As the district court correctly concluded, counsel’s failure to obtain these relevant records constituted deficient performance.
In sum, defense counsel’s investigation into classic mitigators was extremely limited. Two of the district court’s conclusions were clearly erroneous: that counsel was unaware of some mitigators and that counsel conducted sufficient interviews to investigate the mitigators of which he was aware. The district court correctly concluded that counsel failed to obtain relevant records that were available at the time. Taken together, this evidence demonstrates that counsel’s investigation into classic mitigators was unreasonably limited-that counsel’s penalty phase representation was constitutionally inadequate.
Of course, Correll’s attorney was not wholly without a mitigation strategy. But the limited strategy that he developed was unreasonably constricted, and even with respect to that anemic strategy, counsel’s investigative efforts were unreasonably weak.
Defense counsel testified that the principal mitigation evidence he sought was in*946formation that would show Correll as a “good person” and one who had “done good deeds.” Such a limitation on the scope of the mitigation investigation was, in and of itself, unreasonable given the extreme unlikelihood that any testimony about Correll’s character would have been sufficient to “humanize[] him during the time frame of the murder conspiracy at issue.” Allen v. Woodford, 366 F.3d 823, 851 (9th Cir.2004). Rather, as Correll’s attorney knew at the time, the most likely type of evidence available was the type that would portray Correll as a “person whose moral sense was warped by abuse, drugs, [or] mental incapacity.” Id.
Even assuming, however, that rebanee on a character defense was a reasonable strategy in this case, counsel’s investigation into character evidence was inadequate. For example, Correll’s attorney was aware that a chaplain with the California Youth Authority, Reverend Curry, might have been willing to testify on Cor-rell’s behalf, but the attorney never even attempted to contact Reverend Curry.2
Based on the foregoing, we conclude that Correll’s counsel provided constitutionally deficient representation during his investigation into possible mitigation defenses. The district court was correct in its limited holding that defense counsel failed to seek and obtain mental health and other medical records, and we further conclude that the rest of defense counsel’s investigative efforts, including his contact and consultation with Correll, his interviews with relevant witnesses, and his development of a character-based mitigation strategy, were also constitutionally inadequate. Defense counsel’s failure to investigate falls far short of any objective standard against which we might measure reasonable attorney performance under the Sixth Amendment.
B
Compounding his errors during the investigative phase of sentencing, Cornell's attorney then presented to the court virtually none of the little mitigating evidence that he had developed. “There is no more important hearing in law or equity than the penalty phase of a capital trial.” Gerlaugh v. Stewart, 129 F.3d 1027, 1050 (9th Cir.1997) (Reinhardt, J., concurring and dissenting). At the penalty phase, a capital defendant has a “constitutionally protected right [ ] to provide the jury with ... mitigating evidence.” Williams, 529 U.S. at 393, 120 S.Ct. 1495. “Failure to present mitigating evidence at the penalty phase of a capital case constitutes ineffective assistance of counsel.” Bean v. Calderon, 163 F.3d 1073, 1079 (9th Cir.1998).
As anemic as the defense counsel’s investigation was, his presentation of mitigating evidence at the penalty phase was worse. In fact, defense counsel put on no affirmative penalty phase defense whatsoever. He did not call a single witness to testify. He did not introduce any evidence. The state trial court record states: “Defendant waives presentation of mitigating evidence.”
Indeed, the only proactive effort that Correll’s attorney made at sentencing was to write a short response to the presen-tence report. In that written submission, he included a list of mitigating arguments, *947but he did not support those arguments with any evidence, affidavits, or testimony. The entirety of the written submission in mitigation reads as follows:
A. Defendant was under the influence of alcohol and drugs at the time the offenses were committed.
Guy Snelling stated in an interview with police officers on April 12, 1984, that there was alcohol on the breath of Defendant at the time the offenses were committed. It is obvious from this and the conduct of the perpetrators, that they were under the influence of alcohol or drugs or both at the time the offenses were committed.
B. Defendant was only a follower in the commission of the crimes.
Guy Snelling stated in an interview with defense counsel on August 14, 1984 that it was clear that John Na-bors was the leader of the two perpetrators and was making the decisions. This is further corroborated by the fact that it was John Nabors who knew Guy Snelling would have illicit drugs and money and therefore, John Nabors must have done the planning of the robbery.
C. Prior to the robbery, there was no reason to believe that anyone would be present other than Guy Snelling, and therefore, there was no prior plan to kill Debra Rosen, Robin Cady or Shawn Di’Brito.
D. Defendant has cooperated with the Adult Probation Office in the preparation of his presentence report.
E. Defendant’s age.
Predictably, the Arizona Supreme Court and the federal district court concluded that this mitigation argument was not sufficiently significant to call for leniency.
The anemia of counsel’s mitigation presentation was a critical error, certainly rising to the level of constitutionally deficient representation. “The failure to present mitigating evidence during the penalty phase of a capital case, where there are no tactical considerations involved, constitutes deficient performance, since competent counsel would have made an effective case for mitigation.” Smith v. Stewart, 189 F.3d 1004, 1008-09 (9th Cir.1999).
The error’s full magnitude, however, does not become apparent until we consider the effect it had under Arizona law in particular. At the time of the penalty phase proceedings, Arizona law mandated the death penalty if the trial judge found any one of the enumerated aggravating factors and determined that there were no mitigating factors that were sufficiently substantial to call for leniency. Ariz.Rev. Stat. § 13-703 (1984). One of the enumerated aggravating circumstances is a previous violent felony, for which Correll unquestionably qualified. State v. Correll, 715 P.2d at 731. In Correll’s case, therefore, the failure to present any evidence in mitigation “all but assured the imposition of a death sentence under Arizona law.” Summerlin, 427 F.3d at 640; see also Evans v. Lewis, 855 F.2d 631, 637 (9th Cir. 1988) (noting that in Arizona, once an aggravating circumstance like a prior aggravated felony was found, death was inevitable without mitigating evidence, and thus holding that the failure to pursue psychiatric evidence constituted prejudicially deficient performance).
In fact, the State argued five aggravating factors, and Correll’s defense counsel disputed only a few of them. He disputed that the crimes were cruel, heinous, and depraved, and he argued that convictions for more than one homicide could not be used as an aggravating factor because the statute authorizing this factor was not in effect on the offense date. At the eviden-tiary hearing in the district court, he conceded that he thought “it was a veritable certainty” that the court would find “at *948least two, and probably all five of [the] aggravating factors.” The court found four.
Defense counsel’s sentencing memo does not even attempt to rebut three of the five aggravating factors urged by the State. In his oral presentation at sentencing, counsel mentioned the aggravating factors, but in form only, without any substantial legal position or evidentiary support. The entirety of his oral argument at the penalty phase consists of approximately 7 pages of transcript.
Given counsel’s virtual concession of most of the aggravating factors argued by the State and his waiver of the presentation of mitigation evidence, the outcome was obvious: imposition of the death penalty. The Arizona Supreme Court, in reweighing the aggravating and mitigating factors, found no mitigating factors “sufficiently substantial to call for leniency.” State v. Correll, 715 P.2d at 735. The Court highlighted the lack of evidence presented in mitigation and noted that the “defendant has offered no evidence or expert testimony on which we could base a finding that he was unable to appreciate the wrongfulness of his conduct.” Id. The Court was particularly dismissive of his attempt to count cooperation in the pre-sentence investigation as a mitigating factor, noting “[i]t is in defendant’s interest to cooperate at sentencing; defendant should not be rewarded for self-serving acts.” Id.
In sum, Correll’s counsel was constitutionally deficient in failing to investigate and present mitigating evidence. Particularly in light of Arizona’s death penalty regime, the failure to develop a robust mitigation defense-and the failure to defend against the State’s aggravation case-was unreasonable, falling below any objective standard of adequate representation.
C
The State contends that the failure to put on penalty phase evidence was a strategic choice, protected under Strickland. To be sure, under Strickland, we must defer to trial counsel’s strategic decisions. “A reasonable tactical choice based on an adequate inquiry is immune from attack under Strickland.” Gerlaugh, 129 F.3d at 1033. However, to be considered a constitutionally adequate strategic choice, the decision must have been made after counsel has conducted “reasonable investigations or [made] a reasonable decision that makes particular investigations unnecessary.” Strickland, 466 U.S. at 691, 104 S.Ct. 2052. In addition, “[e]ven if [a] decision could be considered one of strategy, that does not render it immune from attack — it must be a reasonable strategy.” Jones v. Wood, 114 F.3d 1002, 1010 (9th Cir.1997) (emphasis in original). In this ease, because of defense counsel’s failure to investigate potential mitigation evidence, he had too little information to make any informed strategic decision. Furthermore, when considered objectively, his purported “strategy” cannot be considered reasonable.
1
A decision by counsel not to present mitigating evidence cannot be excused as a strategic decision unless it is supported by reasonable investigations. See Williams, 529 U.S. at 394, 120 S.Ct. 1495 (recognizing a constitutional right to present mitigating evidence to the jury); Silva, 279 F.3d at 843 (recognizing “the breadth of a criminal defendant’s constitutional protection against his attorney’s failure to investigate mitigating evidence when defending his client against a capital sentence”). In Wiggins, the Supreme Court held that the traditional deference owed to the strategic judgments of counsel is not *949justified where there was not an adequate investigation “supporting those judgments.” 539 U.S. at 521, 123 S.Ct. 2527.
Here, as we have discussed, defense counsel failed to make a reasonable investigation into potential mitigating evidence. Therefore, his decision not to put on a mitigation case cannot be considered to be the product of a strategic choice. An uninformed strategy is not a reasoned strategy. It is, in fact, no strategy at all. Cf. Strickland, 466 U.S. at 690-91, 104 S.Ct. 2052 (holding that “strategic choices made after less than complete investigation are reasonable precisely to the extent that reasonable professional judgments support the limitations on investigation”).
In Silva, for example, we held that in the absence of diligent investigation, counsel cannot make a reasoned tactical decision regarding whether or not to present mitigating evidence. 279 F.3d at 846-47. Indeed, we determined that even if a client forecloses certain types of mitigation evidence, “it arguably becomes even more incumbent upon trial counsel to seek out and find alternative sources of [mitigating evidence].” Id.
Here, an abundance of classic mitigation evidence existed. However, counsel failed to investigate these potential avenues and was therefore unable to make an informed decision as to whether to present the evidence and arguments that were available. His choice not to present mitigation evidence, therefore, cannot be justified as strategic.
2
To the extent that there was any strategy involved in the penalty phase presentation, it cannot be considered a reasonable strategy by any objective measure.
Defense counsel chose to rely on the pre-sentence report prepared by a state probation officer, despite his own characterization of that report as “one-sided.” During his short sentencing argument, defense counsel criticized the author of the pre-sentence report for failing to interview several people who could have provided mitigating statements. The irony, of course, is that defense counsel could have introduced during the penalty phase the very mitigating evidence that he felt the probation officer should have gathered.
The sentencing report described the crimes as “particularly heinous” and speculated that “the murder scene in the desert must have been particularly gruesome.” The probation officer concluded that, given the circumstances of the crime, “[t]hey obviously planned the murders ahead of time and then calculatingly and unemotionally carried out their plans.” The pre-sentence report described Cor-rell’s history as “a text book of psychopathology,” and “riddled with instances of violent behavior and armed aggression.” The probation officer determined that Cor-rell “was not capable of functioning in society.” The report concluded with the observation that “[h]e is a threat, a menace, and in my opinion, the community at large should never again be subjected to the risk of recurrence of this type of behavior.” These statements are hardly the words of mitigation, and no competent capital defense counsel would have relied upon such a report as providing mitigation evidence, much less as the sole source of mitigation evidence.
Defense counsel testified at the eviden-tiary hearing that he “was basically hoping [the judge] would think it was a one-time incident and want to give Mr. Correll a break and find a mitigating factor.” However, the pre-sentence report contained explicit references to an extensive criminal history that belied this theory. Indeed, the page and a half of criminal convictions reported is longer than defense counsel’s *950entire mitigation presentation in his sentencing memorandum. It was not a reasonable strategy to rely on the pre-sen-tence report to prove that the crime was a “one-time incident” when the entire report drew the opposite conclusion.
When asked at the evidentiary hearing, “what was your sentencing strategy,” trial counsel responded that it was “hoping that [the judge] liked Mr. Correll” and hoping that the judge found that the crime “was a drug ripoff that went bad[,] that Michael was under the influence,” and that “he wasn’t the leader in the crimes.” When pressed, however, defense counsel was forced to admit that portraying the crime as a onetime drug ripoff gone bad was not something that would constitute a mitigating factor.
Throughout the evidentiary hearing, defense counsel revealed a fundamental misconception of mitigation evidence. He referred to the sentencing hearing as “a dog and pony show” and “so much smoke.” He said he felt that the judge would not have been receptive to mitigation evidence that was “touchy-feelly [sic] fuzzy-headed kind of stuff.” When asked about the classic mitigation evidence that was available, such as potential brain injury,3 a history of drug addiction, and abuse suffered as a child, counsel testified that he didn’t think of the evidence as favorable evidence. However, it is precisely this type of evidence that the Supreme Court has deemed “powerful.” Wiggins, 539 U.S. at 534,123 S.Ct. 2527.
It appears clear from examination of his testimony that defense counsel was afraid of the sentencing judge. In fact, he forewent psychological testing because he feared that the judge would learn of it, and he testified that he might have presented evidence of Correll’s history of drug addiction had he been before a different judge.4 He believed that the judge would use mitigating evidence as an aggravating factor, in violation of the mandatory language of Ariz.Rev.Stat. § 13-703(E). When asked in a pre-hearing interview about his decision not to introduce evidence of Correll’s psychological disorders, counsel responded:
[A]s a practical matter, and certainly with Judge Howe [the trial judge], once he found out that this man was a sociopath or psychopath, whichever term you want to use, he didn’t have a chance in a hundred of keeping from getting the death penalty. ‘Cause even though he can claim that this is a mitigating factor the reality is that when you tell someone in society and certainly Judge Howe, the man is a sociopath, that dictates that *951he’s the kind of person who should get the death penalty, that’s what the thinking’s going to be.
This entire line of reasoning, however, presumes that the judge would not follow the law5 — speculation that is never appropriate and that is not supported by the record here.
Fear of a particular sentencing judge’s reaction also ignores the fact that, in capital cases, the Arizona Supreme Court conducts an independent review of the aggravating and mitigating factors, reweighing them afresh. See State v. Johnson, 147 Ariz. 395, 710 P.2d 1050, 1055 (1985) (“Whenever the trial court imposes the death sentence we must conduct an independent review of the facts that established the aggravating and mitigating circumstances in order to determine for ourselves if the latter outweigh the former and justify the sentence.”); see also State v. Richmond, 114 Ariz. 186, 560 P.2d 41, 51 (1976) (“[T]he gravity of the death penalty requires that we painstakingly examine the record to determine whether it has been erroneously imposed.”). At the time of Correll’s appeal, the Arizona Supreme Court was also required to conduct an independent proportionality review. State v. Correll, 715 P.2d at 737-38. Therefore, even if defense counsel’s fears about the judge were legitimate, there is no strategic excuse for failing to put on evidence in support of statutory mitigating factors that the Arizona Supreme Court could have considered in its independent re-weighing of aggravating and mitigating factors.
In short, to the extent that defense counsel had a strategy at all, it cannot be considered an objectively reasonable strategy.
3
Counsel’s ineffective assistance at sentencing cannot be excused as strategic. He failed to conduct an investigation sufficient to make an informed judgment. To the extent that his decisions reflected any tactical considerations, his approach of not putting on a mitigation case cannot be considered an objectively reasonable strategy, even when viewed under the highly deferential Strickland standard.
Ill
It is, of course, not enough for Correll to establish that his counsel’s performance at sentencing fell below an objective standard of reasonableness. He must also “show that there is a reasonable probability that, but for counsel’s unprofessional errors, the result of the proceeding would have been different.” Strickland, 466 U.S. at 694, 104 S.Ct. 2052. A reasonable probability is a probability sufficient to “undermine confidence in the outcome.” Id.
In considering this question, we have recognized that deficient performance and prejudice questions may be closely related. See Summerlin, 427 F.3d at 643 (“[W]e conclude that the failure of trial counsel to investigate, develop, and present mitigating evidence at the penalty phase hearing has undermined our confidence in the sentence of death imposed by the trial judge.”); Smith, 189 F.3d at 1011 (“Because of [counsel’s] failure to provide competent representation, our confidence in the outcome of Smith’s sentencing has been undermined.”). In establishing prejudice under Strickland, it is not necessary for the habeas petitioner to demonstrate that the newly presented mitigation evi*952dence would necessarily overcome the aggravating circumstances. Williams, 529 U.S. at 398, 120 S.Ct. 1495. Accordingly, even where the facts discovered on habeas review do not rise to the level of statutory mitigation, we have held that a reasonable probability existed that this information could have affected the sentence. Smith, 140 F.3d at 1270; see also Rompilla, 125 5.Ct. at 2469 (noting that “although we suppose that [the sentencer] could have heard it all and still have decided on the death penalty, that is not the test”).
Here, there was a substantial amount of classic mitigating evidence that could have been presented, but was not.
Correll had endured an abusive childhood. His mother was a Jehovah’s Witness, whose commitment to her church came before her commitment to her family. She spent most of her time with the church, often neglecting her six children’s basic needs. The children were required to attend adult bible study class with her three nights a week, for three hours per night. If they misbehaved or indicated that they were confused or did not understand the religious doctrine, they were punished. Correll’s father was largely absent but sometimes aided his wife in physically punishing their children. There was evidence of incest in the family.
When Correll was seven, a brick wall collapsed on his head. Although he was unconscious for some time after the accident, his parents did not seek medical treatment until several days later when he was still not back to normal. Several experts testified that this type of accident and the symptoms Correll exhibited then and now indicate a high likelihood of brain impairment.6
Against this backdrop, Correll began experimenting with alcohol and drugs around age ten. He was using marijuana, LSD, and amphetamines regularly by age twelve, behavior that can be characterized as self-medication for the everyday trauma of his life and for the mental health illnesses that were later diagnosed when he became a ward of the state.
It is notable that each of the six Correll children reported that they had or have had substance abuse problems beginning in childhood or adolescence. Further, at least five of the six children spent time in juvenile correctional facilities, and all four of the boys in the family have spent time in adult correctional facilities.
In response to Correll’s obvious substance abuse problems, his parents intervened with beatings and threats of kicking him out of the house. Further, the state failed to recommend drug or alcohol treatment despite Correll’s frequent contact with the juvenile authorities.
*953After Correll was shot in the arm at age 14, the hospital asked his parents to let him come home. They allowed him to recuperate at home for three or four days before asking the state to sever their parental rights. At that time, they cut off all communication with their son and considered him dead, as required by their church’s teachings.
Correll became a ward of the state at age 14 and spent his teenage years in various state institutions described as “gladiator schools,” which were characterized as cruel and inhumane, even by those who worked there. He was placed in programs for low-performing students, which were referenced as “dummy shacks.” Within months of becoming a ward of the state, 14-year-old Correll became addicted to heroin.
Correll was committed to psychiatric institutions at least twice during his teen years and was described at age 16 as “severely psychologically impaired.” He was treated with a tranquilizer/anti-psychotic drug while institutionalized, and he attempted suicide on two occasions. However, there is no evidence that Correll continued to receive treatment after these stays.
Methamphetamine eventually became Correll’s drug of choice, which he used whenever he could. Correll offered expert testimony during the evidentiary hearing of the effect of high methamphetamine use, including brain damage, blackouts, and methamphetamine-induced psychosis, all of which may be compounded by sleep deprivation.
At the time of the murders, Correll was injecting a quarter gram to a gram of methamphetamine in one shot, and he was injecting three to four shots a day. According to expert testimony at the eviden-tiary hearing, Correll was in the top 1% of methamphetamine users in terms of quantity. During the period of time in which the crimes were committed, Correll’s typical pattern was to go seven to ten days without sleep, followed by one to two days of continuous sleep. He was observed injecting methamphetamine shortly before the crimes were committed. Expert testimony indicated that he was likely having impulse control problems, judgment impairment, and aggressiveness at the time of the crime and that he may have been experiencing drug-induced paranoia.7
In sum, there was a substantial amount of mitigating evidence available,8 which, taken together, is sufficient to raise a pre*954sumption of prejudice under the Supreme Court’s standard in Wiggins, 539 U.S. at 584-38, 123 S.Ct. 2527.
But we need not rest on presumption. All of the available evidence constituted classic mitigation evidence that certainly had the potential to persuade “an objective fact-finder” that Correll was, at the time of the crimes, incapable of appreciating the wrongfulness of his conduct. Summerlin, 427 F.3d at 643. To use the Supreme Court’s words, “[h]ad[a] jury been able to place petitioner’s excruciating life history on the mitigating side of the scale, there is a reasonable probability that at least one juror would have struck a different balance.” Wiggins, 539 U.S. at 537, 123 S.Ct. 2527.
Indeed, in this case, the evidence of Correll’s “excruciating” history could have provided an alternative — and much more sympathetic — context for the horrific observations and conclusions that were before the judge in the presentence report. While the presentence report characterized Correll as a “threat” and a “menace,” the evidence of Correll’s family history, personality disorder, and brain injury could have colored Correll as an organically diseased and injured person who, through no fault of his own, lacks the ability to comprehend the immorality of his conduct. Correll’s full history also had the potential to convince an objective fact-finder that his criminal behavior has, throughout his life, been his means of gaining the negative and destructive attention that he was taught to seek from a very young age. As the Supreme Court has consistently instructed, these kinds of claims constitute classic mitigation, which a fact-finder must consider when deciding between life imprisonment and death.
Perhaps more compellingly, the evidence of Correll’s methamphetamine use on the night of the crimes, had it been fully presented, could have risen to the level of a statutory mitigator. Under Arizona law, gross intoxication at the time of the crime constitutes a statutory mitigator if that intoxication impaired the defendant’s “capacity to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of law.” A.R.S. § 13-703(G)(1). There was undisputed evidence adduced at the evidentiary hearing that Correll was addicted to methamphetamine, that Correll used some methamphetamine on the day of the crime, that Correll habitually used methamphetamine in astonishingly and unusually high dosages, and that drug addicts generally are incapable of using their drug of choice in any dosage that is lower than their usual dosage. Thus, the evidence strongly indicated that Correll used an extremely high dosage of methamphetamine on the day of the crime.
The district court, however, concluded that there was no evidence of gross intoxication at the time of the crimes because certain witnesses indicated that Correll was oriented during the commission of the crimes. This conclusion rests on a critical misunderstanding of the evidence.
At the evidentiary hearing, expert testimony made it clear that gross methamphetamine intoxication, unlike gross alcohol intoxication, is not necessarily apparent to outside observers. The experts described a state known as “methamphetamine blackout,” during which the user would be capable of performing complex tasks but would be incapable of understanding or remembering his behavior. One of the experts, a recovered methamphetamine addict, specifically confirmed the possibility that “those observing a person in a methamphetamine blackout [wouldn’t] know that the person is in a methamphetamine blackout.” This evidence severely undermines the propriety of the district court’s reliance on witness observation in concluding that Correll was not intoxicated on the night of the crimes. *955Those witnesses might not have known whether Correll was intoxicated or not.
Furthermore, the experts also testified that gross methamphetamine intoxication impairs a person’s inhibition and judgment, rendering the intoxicated person incapable of measuring and understanding the consequences of his actions. A person in a methamphetamine blackout, the experts implied, would not be capable of understanding the “wrongfulness of his conduct.”
Thus, the district court was clearly wrong to conclude that there was no available evidence that Correll was grossly intoxicated — to the point of being unable “to appreciate the wrongfulness of his conduct” — on the night of the crime. Expert testimony at the evidentiary hearing clearly established that methamphetamine use, in the quantities that Correll undisputably used the drug on a regular basis, would significantly impair judgment and consciousness without causing perceptible symptoms of intoxication. We conclude that this evidence — had it been developed and presented — could reasonably be expected to persuade an objective fact-finder that Correll was incapable of understanding the wrongfulness of his conduct on the night of the murders.
The dissent argues that Correll was not prejudiced by the failure to investigate and present mitigation evidence and argument because the presentation of such evidence and argument “would have enabled the prosecution to present very damaging evidence in rebuttal.” However, a significant portion of that damaging rebuttal evidence was already available through the pre-sen-tence report. For example, the “numerous escapes from mental health treatment facilities” and the “hostage taking and armed aggression against mental health workers” were both clearly delineated in the pre-sentence report.
Furthermore, all of the so-called “damaging rebuttal evidence” could, in the hands of a competent attorney, have been used to support Correll’s claims of dysfunctional upbringing and continuing mental disorder. For example, Correll’s statement that he felt “a strong sense of power and excitement” when he committed armed robbery could show either that Cor-rell is dangerous — as the presentence report concluded — or that Correll has a diseased perception of social interaction, which prevents him from conforming his conduct to the law. Indeed, all of the facts on which the dissent relies could be either dehumanizing or mitigating, depending on the context and history given for each cited fact.9
In view of the record developed at the evidentiary hearing, we conclude that there is a reasonable probability that the outcome of Correll’s sentencing would have been different had he received competent representation. This was an unusual case in the capital context because it involved a defendant who had not killed any of the victims, although he certainly attempted to kill one person who fortunately survived. The actual murders were committed by another person. The failure to present a mitigation case was particularly indefensible under Arizona law that existed at the time, which required the imposition of the death penalty absent a case in mitigation. Given all of these factors, there is a significant possibility that the introduction of some mitigating evidence could have spared Correll’s life.
IV
Correll was constitutionally entitled to the presentation of a mitigation defense. *956He did not receive one, although substantial mitigation evidence existed. Most importantly, because Arizona law required the imposition of a death sentence if aggravating factors were proven and no mitigating factors presented, the failure to present any mitigation defense constituted ineffective assistance of counsel under the standards set forth in Strickland. The fear of a trial judge cannot be considered strategic justification for forgoing the presentation of a mitigation defense, particularly given that (1) Arizona law required imposition of the death penalty when no mitigating factors were found, and (2) the Arizona Supreme Court was required to re-weigh the aggravating and mitigating factors. Furthermore, the evidence adduced at the evidentiary hearing revealed several classic mitigators that a reasonable attorney could have used to contextualize Correll’s violent past and to mitigate Correll’s current culpability.
We conclude the Correll is entitled to relief in the form of a new penalty phase trial. We reverse the judgment of the district court and remand with instructions to issue a writ of habeas corpus.
REVERSED.
. As the district court found, some of these records were destroyed between the time of the trial and the time of the habeas investigation.
. The district court concluded that this failure was not prejudicial because Reverend Curry's employer did not permit him to testify on Correll’s behalf. The district court, however, completely misunderstood Reverend Curry’s testimony. The California Youth Authority prohibited Reverend Curry from initiating contact with Correll’s attorney, but it did not prohibit him from appearing on Correll’s behalf at the hearing. Reverend Curry testified repeatedly that he would have been happy to speak on Correll’s behalf if Correll’s attorney had initiated contact (which, again, he never did).
. As the district court noted, the Arizona Courts place significant weight on brain injuries as mitigating evidence. Similarly, "[w]e have repeatedly held that counsel may render ineffective assistance if he is on notice that his client may be mentally impaired, yet fails to investigate his client’s mental condition as a mitigating factor in a penalty phase hearing.” Caro v. Woodford, 280 F.3d 1247, 1254 (9th Cir.2002) (internal quotations omitted).
. The dissent characterizes this decision not to present psychological evidence as strategic because it would "make it easier for the judge to sentence Correll to death because it would cause him to view Correll as permanently psychologically damaged.” However, counsel's failure to investigate Correll's psychological history for fear of the trial judge cannot be termed "strategic.” Counsel worried that the trial judge would presume that any psychological evaluation portrayed Correll in a negative light if he granted a contact visit order for such an evaluation and the results were never submitted to the court. This fear presumes that the trial judge would act inappropriately by considering evidence outside of the record in making his sentencing decision, and it fails to recognize the importance of creating a record for review, even if the trial judge likely would be unsympathetic. Psychological injury is the type of evidence the Supreme Court has viewed as classic mitigating evidence. Wiggins, 539 U.S. at 534, 123 S.Ct. 2527.
. See State v. Vickers, 129 Ariz. 506, 515, 633 P.2d 315, 324 (1981) (holding that personality disorders, while they do not qualify as statutory mitigators, must be considered as potential mitigators, particularly where there is evidence that the personality disorder influenced the defendant's behavior).
. The district court dismissed evidence of Correll’s brain injury, concluding that any organic brain injury played no role in Cor-rell’s crimes. The district court’s conclusion was based on the judge’s own evaluation of two conflicting experts. But in the procedural context of this case, the district court’s role was not to evaluate the evidence in order to reach a conclusive opinion as to Correll’s brain injury (or lack thereof). The district court should have decided only whether there existed a "reasonable probability” that "an objective fact-finder” in a state sentencing hearing would have concluded, based on the evidence presented, that Correll had a brain injury that impaired his judgment at the time of the crimes. Summerlin, 427 F.3d at 643. Because the competing neuropsychologists who testified at the evidentiary hearing agreed that the evidence of brain injury was at least strong enough to deserve presentation at a sentencing hearing, we conclude that Correll’s evidence had at least a "reasonable probability” of persuading an objective fact-finder. The district court clearly erred when it concluded that Correll presented insufficient evidence of organic brain damage.
. The district court discounted much of this evidence on the ground that it was based on Correll’s self-reported drug habits, which the court concluded were not credible. The conclusion that Correll’s reports were not credible, however, is clearly erroneous in light of the substantial corroborating evidence introduced at the evidentiary hearing. Two witnesses, Dawn Day and Reverend Curry, testified as to their own observations of Correll’s drug habits, and their observations fully comported with Correll's self reports. Medical and prison records indicated that Correll had issued identical self reports at times when he had no incentive to exaggerate the extent of his drug abuse. Furthermore, Correll’s reports of his drug use have never varied, over the course of several decades. In short, there was no reason for the district court to doubt the veracity of Correll's self reports. On the contrary, there was significant evidence tending to corroborate Correll’s account, including several records showing consistency over time of Correll’s story.
. The government argues that much of this evidence was already before the sentencing court in the pre-sentence report. While the bare facts of Correll’s troubled past were indeed presented to the court, without further investigation and presentation of contextual' evidence and argument, such facts served only to demonize Correll rather than to mitigate the appropriateness of imposing the death penalty for his actions.
. That some of the defense witnesses at sentencing might have presented inculpatory testimony is not particularly significant, given that counsel had abandoned at sentencing any claims of actual innocence or misidentification.