dissenting.
Clark’s post-conviction counsel in this case has developed extensive evidence of congenital organic brain damage and has shown that effective trial counsel would have investigated and developed such evidence for submission to the jury at the mitigation phase of the case. Such evidence would have given Clark’s counsel a good basis for arguing in favor of reduced culpability. Despite having notice that Clark suffered from brain damage, his trial counsel failed to have him examined by an expert with training in neuropsychology and failed to present any evidence of this congenital brain defect to the sentencing jury. Exactly the same basic pattern occurred in Rompilla v. Beard, — U.S. -, 125 S.Ct. 2456, 162 L.Ed.2d 360 (Jun. 20, 2005), in which the Supreme Court held that a failure to investigate and consequential failure to develop evidence of organic brain damage constituted ineffective assistance of counsel under the Sixth Amendment. The Ohio court’s decision and our Court’s decision are irreconcilable with Rompilla and other Supreme Court precedent concerning the duty of counsel to investigate mitigating evidence in capital cases.
Clark’s primary contention concerning the sentencing phase of his trial is that trial counsel was constitutionally ineffective in its failure to investigate and present evidence of Clark’s organic brain damage. In support of this claim, Clark included in his habeas petition an affidavit and report by a neuropsychologist. Dr. Michael Gel-bort examined Clark in June of 1996. Dr. Gelbort found that “[t]he patient exhibits an Organic Brain Syndrome (OBS).” Gel-bort concluded that the condition was likely congenital and exacerbated by drug abuse and the “asphyxia/hypoxic event or brain injury” that occurred when Clark attempted suicide. Gelbort additionally found that the condition was present at the time of the criminal act and that this congenital condition significantly contributed to Clark’s neuropsychological dysfunction.
*291The state courts found that the failure to investigate Clark’s neurological deficiencies and present evidence similar to that contained in Dr. Gelbort’s report failed to satisfy either the deficiency or the prejudice prong of Strickland. The District Court denied Clark’s habeas petition on this ground finding the Ohio courts’ reasoning persuasive. This Court could affirm the District Court’s decision only by giving short shrift to the record and ignoring the clear impact of important recent Supreme Court opinions concerning the duty of an attorney in- a capital case to fully investigate evidence in mitigation. See Rompilla, 125 S.Ct. at 2462; Wiggins v. Smith, 539 U.S. 510, 123 S.Ct. 2527, 156 L.Ed.2d 471 (2003). Even when applying the deferential standard mandated by 28 U.S.C. 2254(d)(1), the Ohio state courts treatment of Clark’s Sixth Amendment claim involved an unreasonable application of clearly established Federal law as determined by the Supreme Court. See Williams v. Taylor, 529 U.S. 362, 413, 120 S.Ct. 1495, 146 L.Ed.2d 389 (2000).
A. Deficiency
Both the state post-conviction trial court and the Ohio Court of Appeals found that Clark’s counsel was not deficient in its failure to further investigate Clark’s brain damage. State v. Clark, 1998 WL 484119 at *6-*8 (Ohio Ct.App.1998). The only stated reason to support this conclusion, a reason reported by our Court, was the fact that his medical condition was not apparent to those untrained in neuropsychology. Id. Both courts point to a statement in Dr. Gelbort’s report that seems to support their view: “It should ... be noted that the patient’s presentation is one where the lay person, and even a psychologist not trained in neuropsychology ... could and likely would overlook the deficits.”- Id. at *6, *7. Drawing on that statement, the courts suggest that Clark’s attorneys could not have been deficient in failing to investigate a condition that was undetectable by a lay lawyer.
Yet, this finding on deficiency is patently unreasonable. First, the courts misread Dr. Gelbort’s report concerning whether there should have been further investigation of Clark’s mental deficiencies. While Dr. Gelbort’s report does indicate that Clark’s brain damage was not readily apparent to the untrained eye, it goes on to highlight that Clark’s patient history and test data clearly demonstrated deficiencies and indicated the need for neuropsychological testing.1 Below is Dr. Gelbort’s statement in its proper context. The language ignored by the state courts and our court is underlined:
It should also be noted that the patient’s presentation is one where the lay person, and even a psychologist not trained in neuropsychology (or one who does not have the benefit of the test data) could and likely would overlook the deficits. The analogous situation in physical medicine would be the inability of a layperson, or even a physician, to diagnose a cancer from simple external observation and without the benefit of radiological test data. Despite.the neuropsychological deficits not having an overt, outwardly observable physical manifestation, they are real, readily observable in *292the test data, and the patient’s history is clearly indicative of their presence. Review of the patient’s history obviously signal (and did signal at the time of the original trial) the presence of impaired functioning and should have lead to neuropsychological testing and investigation at that time.
J.A. 269.
More importantly, Clark’s counsel had notice that Clark had suffered brain damage and still failed to conduct further investigation. An expert witness in a pretrial hearing described Clark as suffering from both chronic and acute brain damage.2 The state court’s rationale that the deficiencies were not overt is simply nonsensical in light of the fact that the counsel knew (or should have known) of Clark’s condition. Yet, Clark’s counsel failed to either investigate this neuropsychological condition or present evidence concerning it during the mitigation phase.
One of the essential questions in this type of ineffective assistance of counsel case is: How strong is the lead or the prompting evidence? Should the lead cause trial counsel to investigate organic brain damage that may seriously affect a juror’s view of the defendant’s culpability? With regard to counsel deficiency, the instant case is significantly stronger than the Rompilla case.
In Rompilla, the Supreme Court held that a Pennsylvania petitioner’s trial counsel was deficient in its failure to discover mitigating evidence, including evidence that Rompilla suffered from organic brain damage. 125 S.Ct. at 2464-69. Rompilla’s counsel, while on notice that the Commonwealth would attempt to prove the defendant’s history of violence by introducing his prior conviction for rape and assault, failed to examine the record of that conviction. Id. at 2464. The Court further highlighted that “[i]f the defense lawyers had looked in the file on Rompilla’s prior conviction, it is uneontested they would have found a range of mitigation leads that no other source had opened up.” Id. at 2468. Importantly, while the defense lawyers interviewed Rompilla and members of his family and consulted with three different mental health workers, they did not discover any evidence of mental deficiency for use during the sentencing phase. Id. at 2462-63. Yet when the post-conviction attorneys examined Rompilla’s prison records, they “found plenty of ‘red flags’ pointing up a need to test further.” Following these leads would have brought important mitigating evidence to light:
When they tested, they found that Rompilla “suffers from organic brain damage, an extreme mental disturbance significantly impairing several of his cognitive functions.” ... “Rompilla’s capacity to appreciate the criminality of his conduct or to conform his conduct to the law was substantially impaired at the time of the offense.”
125 S.Ct. at 2469 (emphasis added).
Contrary to our Court’s conclusory opinion that “Rompilla simply does not apply to the present case,” Clark’s case is much stronger than Rompilla, where it took many more steps to get from the lead to *293the final medical diagnosis of brain damage. The Rompilla lawyers were deficient for failing to examine the record of a prior criminal proceeding which had attached to the prior conviction some later imprisonment records. These imprisonment records would have alerted them to the need for further medical testing, which would have revealed organic brain damage. The imprisonment examination did not itself show organic brain damage. In Rompilla, the lead would have required the reading of a prior criminal proceeding and then some old prison records in the same file and then make an inference of brain damage leading to further testing. The dissent in Rompilla points out the multiple steps counsel would have had to take to get to the finding of brain damage. Here, Clark’s counsel would not have been required to dig through an old transcript or look for tell-tale signs that further testing was needed. Instead, trial counsel merely needed to investigate further a known neurological defect, a defect about which Clark’s pre-trial hearing expert witness had already testified. This failure to follow this important lead and failure to investigate this obvious source of mitigating evidence falls far below the level of reasonable performance.
Investigating a known mental defect “is not simply a matter of common sense.” Rompilla, 125 S.Ct. at 2465. In Wiggins v. Smith, 539 U.S. 510, 524, 123 S.Ct. 2527, 156 L.Ed.2d 471 (2003), the Supreme Court embraced the standards for capital defense work promulgated by the American Bar Association (ABA) as a relevant standard by which to judge the reasonableness of counsel’s performance.3 The 1989 ABA guidelines direct counsel in capital cases to “collect information relevant to the sentencing phase of trial including, but not limited to; medical history (mental and physical illness or injury, alcohol and drug use, birth trauma and developmental delays); educational history (achievement, performance and behavior) special educational needs (including cognitive limitations and learning disabilities) ....” ABA Guidelines for the Appointment and Performance of Counsel in Death Penalty Cases § 11.4.1(C), p. 93 (1989).4 The current guidelines are even clearer that it is the duty of capital defense counsel to investigate “neurological damage.” ABA Guidelines for the Appointment and Performance of Defense Counsel in Death Penalty Cases § 10.7 Commentary (rev. ed.2003), reprinted in 31 Hofstra L.Rev. 913, 1022 (2003). This collection of professional norms highlights the importance of mental health investigation in capital eases:
*294“In particular, mental health experts are essential to defending capital cases. Neurological and psychiatric impairment ... are common among persons convicted of violent offenses on death row. Evidence concerning the defendant’s mental status is relevant to numerous issues that arise at various junctures during the proceedings .... [T]he defendant’s psychological and social history and his emotional and mental health are often of vital importance to the jury’s decision at the punishment phase.”
Id. § 4.1 Commentary, reprinted in 31 Hofstra L.Rev. 913, 956. Clark’s counsel would be found deficient in failing to investigate his mental health history even had counsel not been made aware of Clark’s condition by his pre-trial expert. With notice of Clark’s brain damage, counsel’s failure to conduct further investigation is all the more outrageous. Our Court’s opinion to the contrary simply refuses to apply ABA Guidelines and the Rompilla case.
B. Prejudice
Surprisingly, the Ohio courts also held that the failure of Clark’s trial counsel to present evidence of organic brain damage and its effects did not prejudice Clark. The Ohio post-conviction trial court and the Ohio Court of Appeals found that Dr. Gelbort’s testimony concerning Clark’s congenital brain defects “would have been cumulative at best.” State v. Clark, 1998 WL 484119 at *8. The state court asserts that Gelbort’s report echoes the testimony of Dr. Hy Kisin, a clinical psychologist who testified on Clark’s behalf during the sentencing phase of the trial. But, finding Dr. Gelbort’s report to be cumulative flies in the face of logic, the record itself, as well as Supreme Court precedent.
Seemingly, by using the term “cumulative,” the state court was suggesting that similar expert testimony along the lines of Dr. Gelbort’s report would have been redundant or added little to no new information to the record. When testimony or exhibits are found to constitute a “needless presentation of cumulative evidence,” courts can generally refuse to admit the evidence. See Fed.R.Evid. 403. As one of our sister circuits has written, “[ejvidence is ‘cumulative’ when it adds very little to the probative force of the other evidence in the case, so that if it were admitted its contribution to the determination of truth would be outweighed by its contribution to the length of trial, with all the potential for confusion, as well as prejudice to other litigants, who must wait longer for their trial, that a long trial creates.” United States v. Kizeart 102 F.3d 320, 325 (7th Cir.1996); see also, United States v. Ives, 609 F.2d 930 (9th Cir.1979) (“Cumulative evidence replicates other admitted evidence.”). But, there is next to nothing that was presented to the sentencing jury in mitigation that even touches on Clark’s mental deficiencies.
During the direct examination, Kisin testified concerning Clark’s drug abuse, Trial Tr. at 89-90, 93-96; the death of Clark’s father, id. at 91-93; the day of the murder and Clark’s lack of intent to kill, id. at 97-103; Clark’s remorse for the victim’s death and Clark’s suicide attempt, id. at 103-05; Clark’s capacity for rehabilitation, id. at 105-06; and the fact that Clark’s mother and children did not want him to be executed, id. at 107-08. There was absolutely no testimony concerning Clark’s organic brain syndrome or the deleterious effect of this mental defect on his functional capacity. The entire extent of Kisin’s testimony concerning Clark’s mental abilities is as follows:
Q. Now, Doctor, as a result again, every question is prefaced as a result of your interviews and discussions that you had with Joe and other individuals *295that you indicated, did you make any observations with regard to his level of intelligence?
A. Yes.
Q. And what was that observation?
A. That he, at best, operates on a dull normal level of intelligence and at worst in a borderline retarded way.
Id. at 96. The notion that Dr. Gelbort’s testimony concerning congenital brain damage would add nothing to this isolated statement concerning intelligence is simply absurd on its face.
Clark’s trial counsel introduced absolutely no medical evidence concerning his mental deficiencies. Counsel did not produce evidence of Clark’s patient history or intelligence test data. Nor did counsel investigate and present evidence of the impact that drug abuse would have on Clark’s congenital condition. There was absolutely no explanation of Clark’s cognitive limitations. Dr. Gelbort’s report indicates that Clark “is generally below what is considered to be the functional level on academic tests, as well as being functionally illiterate,” and that “those portions [of Clark’s memory] which support higher cognitive abilities such as abstract reasoning and complex problem solving are impaired.” J.A. 267-68. Gelbort further explains that his “grossly impaired” memory functions could not support “higher cognitive functions such as being able to draw from his past experience and upon previously learned lessons.” J.A. 268. Gel-bort’s report also indicated that Clark’s cognitive limitations were exacerbated in new, complex or confusing situations:
[W]ith more demanding cognitive tasks the patient was observed to have errors of impulsivity or to act in a disinhibited fashion. This is to say that, when participating in a complex ambiguous, confusing or rapidly evolving situation, Mr. Clark is likely to produce an impulsive or disinhibited type of response. Problem solving in new/novel situations or conditions was also moderately impaired with adequate performance seen on easier tasks but the patient being cognitively overwhelmed on the more complex measures.
Id.
Yet the state court maintains, and our Court appears to concur, that all of this is nothing new, because the psychologist had already told the jury that Clark “at best, operates on a dull normal level of intelligence and at worst in a borderline retarded way.” The court of appeals reads the incredibly detailed observations of Clark by Dr. Gelbort to be a cumulative reiteration of this one sentence that was presented in the mitigation phase of the case. The record makes clear that there was no serious attempt by trial counsel to investigate Clark’s mental deficiencies or cognitive limitations. As in Rompilla, “[t]his evidence adds up to a mitigation case that bears no relation” to that put before the sentencing jury. Rompilla, 125 S.Ct. at 2469. Courts sometimes decide that they want to reach a particular result, come what may, and simply forget about important facts and inconsistent legal principles. This form of “cognitive dissonance” seems to be what has happened in this case.
Clark was plainly prejudiced by his counsel’s failure to follow up on red flags that appeared during the pre-trial hearing and that should have been discovered by any capital counsel adhering to the prevailing professional norms. The evidence of organic brain damage and cognitive limitations is nearly identical to the evidence that Rompilla’s counsel would have discovered if they had followed up on the leads presented to them in their client’s prison records, and the Supreme Court found that Rompilla was prejudiced by his counsel’s failure to investigate and discover this *296evidence. Rompilla, 125 S.Ct. at 2468-69. The readily available but undiscovered or ignored “mitigating evidence, taken as a whole, ‘might well have influenced the jury’s appraisal’ of [Clark’s] moral culpability.” Wiggins v. Smith, 539 U.S. at 538, 123 S.Ct. 2527 (quoting Williams v. Taylor, 529 U.S. at 398, 120 S.Ct. 1495). This Court should therefore reverse the decision of the District Court. The State of Ohio should either retry the case on penalty or stipulate to a life sentence.
. The guidelines for capital defense work promulgated by the American Bar Association (ABA) undermine the Ohio courts’ suggestion that the difficulty of diagnosis would be a basis for failing to investigate neurological deficiencies: "Counsel’s own observations of the client’s mental status, while necessary, can hardly be expected to be sufficient to detect the array of conditions ... that could be of critical importance." ABA Guidelines for the Appointment and Performance of Defense Counsel in Death Penalty Cases § 4.1 Commentary (rev. ed.2003), reprinted in 31 Hofstra L.Rev. 913, 956-57 (2003).
. Prior to the trial, Clark challenged the admissibility of his confession on the grounds that he was incapable of voluntarily, intelligently, and knowingly confessing to the crime. During a pre-trial hearing, Clark's counsel introduced the testimony of Dr. Emanuel Tanay, a psychiatrist. While Dr. Tanay did not examine Clark personally, he did review his medical records. Based on this investigation, Dr. Tanay testified that Clark had significant brain damage. As the trial court summarized: “Essentially, Dr. Tanay concluded that there was a reasonable medical certainty that Clark suffered both acute and chronic brain damage ....’’ J.A. 273.
. In Wiggins, the Court found that habeas should issue where the petitioner’s trial counsel did not adequately investigate his client's life history. Rather than conducting an investigation, the counsel in Wiggins merely relied on the presentence investigation report and department of social services records. In addition to falling below the standard local practice in defending Maryland capital cases, the Court wrote that the attorney's "conduct similarly fell short of the standards for capital defense work articulated by the American Bar Association-standards to which we long have referred as ‘guides to determining what is reasonable.' ” Id. (citing Strickland, 466 U.S. at 688, 104 S.Ct. 2052; Williams v. Taylor, 529 U.S. at 396, 120 S.Ct. 1495); see also Rompilla, 125 S.Ct. at 2465-66 & nn. 6-7; Florida v. Nixon, 543 U.S. 175, 125 S.Ct. 551, 562, 160 L.Ed.2d 565 (Dec. 13, 2004) (referencing the ABA Guidelines in a habeas challenge based on ineffective assistance of counsel).
. See also Hamblin v. Mitchell, 354 F.3d 482, 487 (6th Cir.2003) ("Although the instant case was tried before the 1989 ABA edition of the standards was published, the standards merely represent a codification of longstanding, common-sense principles of representation understood by diligent, competent counsel in death penalty cases.”).