In 1994, Missouri inmate Jerry Dean King was convicted of first-degree assault and armed criminal action and received two consecutive life sentences for shooting his brother Dennis. King now appeals the denial of his 28 U.S.C. § 2254 petition for a writ of habeas corpus. The issue is whether his trial counsel provided constitutionally ineffective assistance in failing to investigate and present evidence of King’s diminished mental capacity. After a panel of this court reversed, we granted the State’s petition for rehearing en banc and vacated the panel opinion. Concluding that King’s contention is procedurally defaulted and is in any event without merit, we affirm.
I. Factual and Procedural Background.
We state the background facts as summarized by the Missouri Court of Appeals in affirming King’s conviction and the denial of state post-conviction relief. State v. King, No. 19751 (Mo.App. Mar. 24, 1997) (unpublished). In November 1993, King was living in a trailer behind his brother’s home. At 4:00 a.m. on November 30, King came to the door and Dennis’s wife Viola let him in. King told Dennis that he wanted to rob a bank, produced a .22 caliber pistol, and asked Dennis to load it. Den*819nis did so and gave the gun back to King, . who put it in his pocket. After jumping around the room to prepare for the im- ■ pending robbery, King asked his brother for a hug as it would be the last time they-would see each other. After one hug, King asked for another. During the second hug, King pulled out the gun, shot Dennis under the arm, and ordered Dennis and Viola to the floor. Dennis wrestled with King, allowing Viola to escape. Dennis seized the gun, threw it into the front yard, and ran from the house. Viola, hiding in the backyard, heard a second gunshot.
Dennis hid in a gully when he heard King running down the road. King ran to the house of a neighbor, Kenneth Ruark,' and pounded on the door. Ruark opened the door and saw King with a gunshot wound in his leg. King told Ruark that Dennis had shot him. Ruark let King inside and called for help. Five minutes later, Dennis knocked on Ruark’s door. Dennis told Ruark that King had shot him. Ruark helped Dennis inside. When the brothers were together, King hit Dennis several times until Ruark intervened. Dennis repeatedly asked King why he shot him, but King did not reply. King accused Dennis of shooting him in the leg. Dennis replied, “You shot yourself ... to make it look good.”
Prior to trial, Public Defender Victor, Head, representing King, moved for a mental evaluation of his client. The motion was granted, and King was examined by Dr. Harold Robb, senior psychiatrist at the Southwest Missouri Mental Health Center. Dr. Robb’s seven-page report, dated January 26, 1994, was based upon a psychiatric interview with King, the court order directing the examination, the criminal complaint against King, and the police report regarding the incident. The report described in detail King’s education, family and employment history, psychiatric and medical history,1 and personal habits; King’s description of the shooting incident and his relationship with his brother; and Dr. Robb’s opinions as to King’s speech pattern, perception, orientation, insight, judgment, mood, general sensorium, and psychomotor activity at the interview. The report concluded with a' section entitled, “Report of Evaluation in Accordance with Section 552.010, RSMo,” the Missouri statute defining mental disease or defect for purposes of criminal proceedings. Dr. Robb reported:
2. [King] does not suffer from a mental illness or defect as defined in Section 552.010, RSMo.
3. [King] does not suffer from a mental disease or defect that would cause him to lack capacity to understand the proceedings against him or to assist in his own defense. • ,
4. It is my opinion, on the basis of the present examination and background information, that at the time of the alleged criminal conduct, [King] did not suffer from a mental disease or defect that wold cause him not to know or appreciate the nature, quality or wrongfulness of his conduct or make him incapable of conforming his conduct to the requirements of the law.
Following a change of venue, Assistant Public Defender Frank Yankoviz assumed responsibility for King’s defense. At trial, *820King claimed self-defense. He testified that Dennis had urged King to help buy and sell children, and the brothers argued because King did not want to be involved. Dennis retrieved a pistol from anbther room. King tried to grab the gun, and it discharged as he and Dennis wrestled. King claimed that Dennis followed him outside with a rifle, and King was shot in the leg while wrestling Dennis for the rifle. Finding Dennis’s testimony more credible than King’s, the jury convicted King of first-degree assault and armed criminal action. After pronouncing sentence, the trial court asked King whether he was satisfied with attorney Yankoviz’s representation. King responded, “Yes, sir. No question.”2
In June 1995, King — represented by new counsel — filed a motion for post-conviction relief under Missouri Supreme Court Rule 29.15. As relevant to this appeal, King alleged that trial counsel provided ineffective assistance by failing to fully investigate whether King was competent to stand trial and aid in his defense, and whether he “suffered from a mental disease or defect which would exclude criminal responsibility.” At an evidentiary hearing on the motion, King presented the testimony and written evaluations of neu-ropsychologist Dennis Cowan and psychiatrist William Logan. Dr. Cowan noted that King exhibited very marked neurop-sychological dysfunctions, attributing these deficits to King’s gunshot wound to the head, other head injuries, and his history of substance abuse. Dr. Logan opined that King’s gunshot wound caused extensive memory loss, cognitive difficulties, and post-traumatic stress disorder. Both experts opined that King tended to confabulate to fill gaps in his memory, which could render any trial testimony incredible. They also criticized Dr. Robb’s psychiatric evaluation because Robb was aware of King’s head injury but did not obtain his medical records and conduct neuropsycho-logical testing. Dr. Logan concluded that, at the time of the November 1993 shooting, King lacked the ability to understand the nature or quality and wrongfulness of his actions, or to control his actions within the requirements of the law.
After King rested, the State called attorney Yankoviz, who testified that King had instructed him not to pursue an insanity defense “because he didn’t want to end up in a psychiatric institution.” Acknowledging that King had asked Yankoviz to obtain hospital records pertaining to the gunshot wound to King’s head, Yankoviz testified he decided not to obtain those records because King had been “adamant about not pursuing the legal defense of not guilty by reason of mental disease or defect.”
The state trial court denied King’s motion for post-conviction relief, finding that King was competent to stand trial, competent to aid in his defense at trial, did not suffer from mental disease or defect excluding criminal responsibility, and “made a rational decision not to pursue the defense of mental disease or defect excluding responsibility.” Based upon these findings, the court concluded that King had not established ineffective assistance of counsel. King appealed, arguing that Dr. Robb’s report was inadequate and attorney Yankoviz provided ineffective assistance when he “failed to investigate whether [King] was competent to stand trial or criminally responsible for his conduct.” The Missouri Court of Appeals affirmed, *821noting that the trial court “obviously disbelieved the testimony of Drs. Cowan and Logan.”
King then filed this petition for a federal writ of habeas corpus. After quoting at length from the Missouri Court of Appeals decision, the district court3 denied the petition, concluding:
The resolution [of the ineffective assistance claim presented to the state courts] did not result in “a decision that was contrary to, or involved an unreasonable application of, clearly established Federal law, as determined by the Supreme Court of the United States” or in “a decision that was based on an unreasonable determination of the facts in light of the evidence presented in the State court proceeding.” 28 U.S.C. § 2254(d)(1) and (2) (as amended April 24,1996).
On appeal, King raises for the first time a new theory — that Yankoviz provided ineffective assistance by failing to investigate King’s mental condition beyond Dr. Robb’s report, not for the purpose of establishing incompetency to stand trial or lack of criminal responsibility, but for the purpose of presenting a partial defense of diminished mental capacity and of providing the jury “an explanation for the unorganized and seemingly incredible manner in which [King] testified at trial.”
II. The New Theory Is Procedurally Barred.
In his motion for state post-conviction relief, King alleged that trial counsel failed to fully investigate whether King was competent to stand trial and aid in his defense, or if he “suffered from a mental disease or defect which would exclude criminal responsibility.” (Emphasis added.) The state courts denied the motion after an evidentiary hearing, finding that King was competent to stand trial, competent to aid in his trial defense, and “did not suffer from mental disease or defect excluding criminal responsibility.” King’s petition to the district court raised the same ineffective assistance theory. On appeal, he argues for the first time that counsel provided ineffective assistance in not investigating and pursuing the partial defense of diminished mental capacity. That theory was procedurally defaulted in the state courts. It is “the settled law of this Circuit that a habeas petitioner must have raised both the factual and legal bases for each ineffectiveness of counsel claim in the state courts in order to preserve the claim for federal review.” Flieger v. Delo, 16 F.3d 878, 885 (8th Cir.), cert. denied, 513 U.S. 946, 115 S.Ct. 355, 130 L.Ed.2d 309 (1994).
The State did not argue procedural default to our panel. That omission was obviously inadvertent, because the State argues to the court en banc that the diminished capacity theory is defaulted. In Trest v. Cain, 522 U.S. 87, 89, 118 S.Ct. 478, 139 L.Ed.2d 444 (1997), the Supreme Court confirmed that procedural default is an affirmative defense that should be raised by the State, and the Court held that a circuit court is not required to consider the issue sua sponte. The Court did not consider whether a circuit court is permitted to consider the issue sua sponte, but noted that in Granberry v. Greer, 481 U.S. 129, 107 S.Ct. 1671, 95 L.Ed.2d 119 (1987), it had previously held that a circuit court may raise sua sponte a habeas petitioner’s failure to exhaust state remedies. Trest, 522 U.S. at 90, 118 S.Ct. 478; see 28 *822U.S.C. § 2254(b)(3). In the wake of Trest and Gmnberry, at least nine circuits agree “that a federal court, in the exercise of its judicial discretion, may address procedural default despite the failure of the state to preserve or present the issue properly.” Yeatts v. Angelone, 166 F.3d 255, 261-62 (4th Cir.1999) (collecting cases).
We agree with our sister circuits and hold that we have discretion to consider an issue of procedural default sua sponte. We further conclude that this is a case where we should do so. The doctrine of procedural default is particularly appropriate when “an unresolved question of fact or of state law might have an important bearing” on the federal habeas claim. Granberry, 481 U.S. at 134-35, 107 S.Ct. 1671. To our knowledge, no Missouri case has applied the doctrine of diminished mental capacity to a prosecution for first-degree criminal assault. King’s counsel speculates that proof of diminished capacity could result in conviction for the lesser-included felony of second-degree assault, because one form of first-degree assault is to “knowingly cause[ ] or attempt[ ] to cause serious physical injury,” Mo.Ann. Stat. § 565.050.1, whereas second-degree assault is defined as “recklessly causing] serious physical injury,” Mo.Ann.Stat. § 565.060.1(3). But the term reckless “is not self-defining” and in the criminal law generally means disregard of a knovm risk. Farmer v. Brennan, 511 U.S. 825, 836-37, 114 S.Ct. 1970, 128 L.Ed.2d 811 (1994). Because of King’s procedural default, we do not know whether the Missouri courts would permit proof of diminished mental capacity to reduce an offense from first-degree to second-degree assault, and if so, what sort of proof would suffice. These issues of state law are critical in determining both aspects of the Sixth Amendment inquiry under Strickland v. Washington, 466 U.S. 668, 104 S.Ct. 2052, 80 L.Ed.2d 674 (1984), ineffective assistance and prejudice. For these reasons, King’s new theory is procedurally barred.
III. The New Theory Fails on the Merits.
As the district court recognized, under the 1996 amendments to 28 U.S.C. § 2254(d), a federal court may grant habeas relief to a state inmate only if (1) the state court’s decision was contrary to clearly established federal law, as determined by the Supreme Court, or (2) involved an unreasonable application of clearly established federal law, as determined by the Supreme Court.
Under the “contrary to” clause, a federal habeas court may grant the writ if the state court arrives at a conclusion opposite to that reached by this Court on a question of law or if the state court decides a case differently than this Court has on a set of materially indistinguishable facts. Under the “unreasonable application” clause, a federal habeas court may grant the writ if the state court identifies the correct governing legal principle from this Court’s decisions but unreasonably applies that principle to the facts of the prisoner’s case.
Williams v. Taylor, 529 U.S. 362, 412-13, 120 S.Ct. 1495, 146 L.Ed.2d 389 (2000). “[A]n unreasonable application of federal law is different from an incorrect application of federal law.” Id. at 410, 120 S.Ct. 1495 (emphasis in original). In reviewing the state court decision, a fact determination is presumed to be correct and must be rebutted by clear and convincing evidence. 28 U.S.C. § 2254(e).
To prevail on a claim of ineffective assistance, King must show that counsel’s performance was deficient and that King was prejudiced by the deficient performance. See Strickland v. Washington, 466 U.S. 668, 687, 104 S.Ct. 2052, 80 *823L.Ed.2d 674 (1984). Deficient performance means representation that falls “outside the wide range of professionally competent assistance.” Id. at 690, 104 S.Ct. 2052. Prejudice “is a reasonable probability that, but for counsel’s unprofessional errors, the result of the proceeding would have been different. A reasonable probability is a probability sufficient to undermine confidence in the outcome.” Id. at 694, 104 S.Ct. 2052. Here, the state court record, fairly read, establishes that King failed to prove either element of ineffective assistance under Strickland, constitutionally unreasonable legal representation or prejudice.
A. Unreasonable representation. Defense counsel has the “duty to make reasonable investigations or to make a reasonable decision that makes particular investigations unnecessary. In any ineffectiveness case, a particular decision not to investigate must be directly assessed for reasonableness in all the circumstances, applying a heavy measure of deference to counsel’s judgments.” Strickland, 466 U.S. at 691, 104 S.Ct. 2052. In making this assessment, we look to the facts of the particular case, “viewed as of the time of counsel’s conduct.” Id. at 690, 104 S.Ct. 2052.
King argues that Yankoviz knew of King’s prior head injuries and should have procured King’s medical records and a second evaluation of King’s competency, sanity, and mental condition. King bases this contention on attorney Yankoviz’s testimony at the state post-conviction hearing that he never obtained “any other second opinion after the State court-ordered evaluation.” However, that testimony is suspect. Apparently, Yankoviz did not recall the following colloquy at the conclusion of King’s sentencing hearing, some seventeen months previously, when the court raised the question of the fee to which public defender Yankoviz was entitled:
MR. YANKOVIZ: $1,250, Judge.
THE COURT: And what is that for?
MR. YANKOVIZ: $1,000 for the trial. Then there was a pretrial hearing, motion to suppress.
THE COURT: Okay. Any other litigation expense, depositions or anything, as far as you can recall?
MR. YANKOVIZ: We did have an evaluation.
THE DEFENDANT [KING]: Two.
THE COURT: The public defender pay that or the State of Missouri.
MR. YANKOVIZ: No. The second one was out of our pocket, our expense. $250, Judge.
THE COURT: For the mental exam?
MR. YANKOVIZ: Yes, Judge.
THE COURT: So you’re asking for a judgment for $1,500?
MR. YANKOVIZ: Yes, sir.
THE COURT: Okay. Okay. Mr. King, based on the amount of time and expenses spent by the public defender, they’re asking for a judgment against you in the sum of $1,500 to be paid — not to them but to the State of Missouri Public Defender Commission. Do you believe that $1,500 is a reasonable sum for representing you?
THE DEFENDANT: Yes, sir. I do. Actually more because I believe that they’ve went above and beyond their duties to help me. So, I have no problem with that. If I have some means and ways of taking care of that, I will do it regularly.
We conclude that attorney Yankoviz’s contemporaneous representation to the court that he did obtain a second mental evaluation, to which King agreed in open court, is far more credible than counsel’s inconsistent testimony at the post-conviction *824hearing months later. Thus, the record does not support King’s contention that Yankoviz did no further investigation of King’s mental condition beyond Dr. Robb’s report.
In addition, Yankoviz was not ineffective even if he did fail to seek a second evaluation of his client for the purpose of challenging Dr. Robb’s opinion that King was competent to stand trial. King made clear to Yankoviz that he did not wish to be placed in a psychiatric institution, and the consequence of being adjudicated incompetent to stand trial is commitment to the state’s department of mental health. See Mo.Ann.Stat. § 552.020. Counsel was not obliged to disregard both Robb’s report and his client’s wishes and further pursue a determination that his client was not competent to proceed. See LaRette v. Delo, 44 F.3d 681, 685-86 (8th Cir.1995) (counsel’s decision not to pursue competency defense reasonable where defendant insisted he was competent at time of offense and instructed counsel not to pursue such a defense); Sidebottom v. Delo, 46 F.3d 744, 753 (8th Cir.1995) (counsel not compelled to seek second mental evaluation merely because first was less than favorable).
Pressing his new diminished capacity theory, King argues that Yankoviz’s decision to forego further investigation into King’s mental condition was based upon counsel’s ignorance of the diminished capacity partial defense. Again, this contention is based upon Yankoviz’s testimony at the post-conviction hearing. When asked why he did not obtain medical records pertaining to King’s gunshot wound, Yan-koviz replied that “since we weren’t pursuing a legal defense of not guilty by reason of mental disease or defect ... I didn’t think that that would be admissible.” However, Yankoviz was not asked directly whether he was aware of the diminished capacity partial defense. This testimony does not establish counsel’s ignorance.
Under Missouri law, evidence that defendant suffers from a mental disease or defect is admissible “[t]o prove that the defendant did or did not have a state of mind which is an element of the offense.” Mo.Ann.Stat. § 552.015(2)(8). At least for some crimes, such evidence may establish a diminished capacity defense (also known as partial responsibility), permitting the defendant to avoid conviction of a more serious crime in favor of conviction of a lesser offense. See State v. Anderson, 515 S.W.2d 534, 540-42 (Mo.1974) (en banc) (defendant charged with first-degree murder who presented evidence of mental disease or defect entitled to instruction on manslaughter). Because the result is conviction of a lesser crime, this partial defense avoids commitment to a state mental hospital, which is mandated for those acquitted by reason of a mental disease or defect. See Mo.Ann.Stat. § 552.040(2).
However, the diminished capacity partial defense must be based upon a mental disease or defect as defined in Mo.Ann.Stat. § 552.010. See State v. Larson, 941 S.W.2d 847, 854-55 (Mo.App.1997); State v. Foster, 838 S.W.2d 60, 70-71 (Mo.App.1992), cert. denied, 507 U.S. 994, 113 S.Ct. 1607, 123 L.Ed.2d 169 (1993). Dr. Robb’s report concluded that King “does not suffer from a mental illness or defect as defined in Section 552.010, RSMo.” Thus, although Dr. Robb’s report did not specifically address the question of diminished capacity, a competent Missouri criminal defense attorney reading the report would know that it ruled out a diminished capacity partial defense.
For all these reasons, giving attorney Yankoviz’s judgment the “heavy measure of deference” to which it is entitled under Strickland, we conclude the record fully supports the state courts’ determination *825that Yankoviz’s representation did not fall below an objective standard of reasonableness.
B. Prejudice. After considering the testimony of Drs. Cowan and Logan at the post-conviction hearing, the state courts found that King did not suffer from a mental disease or defect as defined in Mo.Stat.Ann. § 552.010. As we have explained, under Missouri law the diminished capacity partial defense must be based upon a mental disease or defect as defined in that statute. Thus, if King had raised the diminished capacity ineffective assistance-theory to the state courts, and z/the Missouri courts would even recognize a diminished capacity partial defense to first-degree criminal assault, this finding would have necessitated its denial because counsel’s failure to ferret out and pursue legally insufficient evidence of diminished capacity did not prejudice King’s defense.
King further argues that his defense was prejudiced by the absence of expert testimony explaining why his trial testimony was meandering and disjointed. However, before King took the stand, attorney Yankoviz cautioned the jury that King “may have a little trouble. He’s been shot in the head before by a cousin.... As a result of being shot in the past, he does have some difficulty remembering — thinking; and he has to think a lot slower than his brother.” Assuming expert testimony offered solely for this purpose would have been admissible,4 there is no “reasonable probability” it would have affected the outcome of the trial by persuading the jury to believe King rather than his brother. King further argues that diminished capacity evidence might have persuaded the trial court to impose a more lenient sentence. But this is rank speculation. In explaining why he sentenced King to two consecutive life terms, the trial judge emphasized King’s criminal history, which included serious violent offenses prior to the gunshot wound to the head, and the nature of King’s unprovoked and life-threatening attack on his brother. Thus, there was no Strickland prejudice.
III. Conclusion.
For the foregoing reasons, we agree with the district court that the state courts’ denial of post-conviction relief was neither contrary to nor an unreasonable application of federal law, as established by Strickland, the applicable Supreme Court precedent. Accordingly, the judgment of the district court is affirmed.
. In the Past Medical History section, Dr. Robb stated that King reported that he was shot in the head by his cousin five to seven years earlier, resulting in a two-week hospital stay, and has had seizures from time to time since then. King told Dr. Robb that he takes medication to prevent the seizures and does not feel that he suffered any ill effects from this injury, apart from, “[when] I’m doing something, [I] forget sometimes what I’m doing.” Dr. Robb did not review King’s medical records regarding this injury.
. The court therefore found no probable cause that King had received ineffective assistance, a finding required by Missouri Supreme Court Rule 29.07(b)(4) that determines whether trial counsel may represent a defendant on appeal and in any post-conviction proceeding. See Shigemura v. Groase, 45 F.3d 250, 251 (8th Cir.1995).
. The HONORABLE DEAN WHIPPLE, Chief Judge of the United States District Court for the Western District of Missouri.
. That is a highly dubious proposition. See Mo.Stat.Ann. § 552.015; State v. Copeland, 928 S.W.2d 828, 837 (Mo.1996) (en banc); State v. Davidson, 941 S.W.2d 732, 735 (Mo.App.1997) (upholding exclusion of expert testimony offered to explain defendant’s inability to recount events at trial).