Vacated and remanded by published opinion. Judge MOTZ wrote the opinion, in which Chief Judge WILKINS joined. Judge SHEDD wrote a dissenting opinion.
DIANA GRIBBON MOTZ, Circuit Judge:
Percy Levar Walton appeals the denial of his second federal habeas petition, contending that his execution would violate the Eighth Amendment. Specifically, he asserts that to execute him would violate both the prohibition against execution of the insane, see Ford v. Wainwright, 477 U.S. 399, 106 S.Ct. 2595, 91 L.Ed.2d 335 (1986), and the prohibition against execution of the mentally retarded, see Atkins v. Virginia, 536 U.S. 304, 122 S.Ct. 2242, 153 L.Ed.2d 335 (2002) (“Atkins I”).1 In his first federal habeas petition, Walton attacked his convictions and death sentences on numerous grounds. The district court denied that petition, and we affirmed. Walton v. Angelone, 321 F.3d 442 (4th Cir.2003) (“Walton I”). Subsequently, however, in the wake of the Supreme Court’s decision in Atkins I, Walton moved for authorization to file a successive § 2254 petition. We granted such authorization to consider both his Atkins claim and his Ford claim, which was premature at the time of his original federal habeas petition. The district court denied both claims. For the reasons that follow, we vacate that judgment and remand for further proceedings.
I.
On October 7, 1997, Walton pleaded guilty to murdering Archie Moore, Elizabeth Kendrick, and Jessie Kendrick in Danville, Virginia. Walton I, 321 F.3d at [288]*288449. The state trial court sentenced Walton to death; the Supreme Court of Virginia affirmed, id. at 450; and, on December 7, 1998, the United States Supreme Court denied Walton’s petition for writ of certio-rari. Walton v. Virginia, 525 U.S. 1046, 119 S.Ct. 602, 142 L.Ed.2d 544 (1998). The state supreme court ultimately denied Walton collateral relief, Walton I, 321 F.3d at 451, and the United States Supreme Court again denied Walton’s petition for writ of certiorari. Walton v. Taylor, 529 U.S. 1076, 120 S.Ct. 1693, 146 L.Ed.2d 499 (2000).
In March of 2000, Walton filed his first federal habeas petition, which the district court denied. Walton I, 321 F.3d at 452. This court, in turn, denied Walton a certificate of appealability as to the claims raised in that petition and dismissed his appeal. Id. at 467. We noted, however, as the district court had, that under the Supreme Court’s decision in Stewart v. Martinez-Villareal, 523 U.S. 637, 118 S.Ct. 1618, 140 L.Ed.2d 849 (1998), Walton’s Ford claim was at that time premature and he would therefore not be barred from raising it again in a subsequent petition. See Walton I, 321 F.3d at 452, 467 n. 21.2
Following our decision, the Commonwealth scheduled Walton’s execution for May 28, 2003. Five days before that date, on May 23, 2003, we authorized Walton to file a successive habeas petition to raise his Atkins claim, and two days later the district court granted a stay of Walton’s execution. In a July 2, 2003 order, the district court dismissed Walton’s Atkins claim on the pleadings, ruling that “Walton has not satisfied the statutory definition of mental retardation under Virginia law.” Walton v. Johnson, 269 F.Supp.2d 692, 700-01 (W.D.Va.2003) (“Walton II”). In the same order, finding “sufficient conflicting evidence,” id. at 701, regarding Walton’s competence to be executed, the court scheduled an evidentiary hearing on Walton’s Ford claim, noting that under Martinez-Villareal that claim was ripe for review. See id. at 696, 702.
Subsequently, the district court held two evidentiary hearings on Walton’s Ford claim. On March 4, 2004, the district court denied that claim, concluding that “Walton understands that he is sentenced to die by execution and that he is to be executed for murdering three people.” Walton v. Johnson, 306 F.Supp.2d 597, 601 (W.D.Va.2004) (“Walton III”).
II.
We first address Walton’s Ford claim.
A.
At the July 2003 Ford hearing, six witnesses testified on Walton’s behalf, including four mental health professionals who had previously treated Walton. Sherri Ann Hopkins, a psychologist charged with monitoring death row inmates at Sussex I State Prison, where Walton is incarcerated, opined that Walton does not understand that he is going to be executed or why he might be executed. “Most people prepare when they’re ... going to Greens-ville,” she said. “He hasn’t prepared whatsoever. I don’t think he knows what’s going to happen to him.” Similarly, Dr. [289]*289Patricia General, a prison psychiatrist who examined Walton several times in April and May 2003, testified that Walton is “floridly psychotic” and does not know what it means that he is going to be executed.
Dr. Anand Pandurangi, director of the schizophrenia program and chairman of inpatient psychiatry at the Medical College of Virginia, also testified on Walton’s behalf. Dr. Pandurangi, who had seen Walton several times since 1999, stated that Walton’s thinking on the subject of death is delusional, as evidenced in part by his desire to have a telephone, a motorcycle, and a job at Burger King, and to look good for a visit to the shopping mall — all after his execution. Dr. Pandurangi also testified that Walton does not understand “[i]n any sustained sort of way” the fact that he is going to be executed and die or why Virginia has sentenced him to death. Finally, Dr. Pandurangi testified that he does not think Walton is competent to assist in his own defense.
Dr. Ruben Gur, director of the brain behavior center at the University of Pennsylvania, corroborated Dr. Pandurangi’s testimony, stating that Walton expressed a desire to “get a Burger King” after his execution. Dr. Gur also testified that Walton does not understand what his execution means. “He does not comprehend what is going on right now as we speak.”
Walton’s testimony seemingly confirmed Dr. Gut’s assessment. In response to repeated questions, Walton failed to communicate sensibly about his sentence or the meaning of his execution:
ATTORNEY: Do you know what your sentence is now, since you’re at Sussex?
WALTON: Nah.
ATTORNEY: Can you take a guess?
WALTON: I got — I got a paper saying that I got a hearing May 28th, 2003.
ATTORNEY: May the 28th, 2003, you have a hearing?
WALTON: Yeah.
ATTORNEY: If you have an execution date, does that mean that you have been sentenced to death?
WALTON: Umm, nah. I don’t think — I don’t think so.
ATTORNEY: What does it mean?
WALTON: I believe — I believe — I believe so, but I don’t know. You know what I’m saying? I don’t know.
ATTORNEY: You believe it does mean you’ve been sentenced to death?
WALTON: No.
ATTORNEY: If I told you, or reminded you, that May 28th, 2003, has already passed ... can you tell me why you weren’t executed on that date?
WALTON: No, I don’t know why. I don’t even know why.
ATTORNEY: Do you have any idea? Can you take a guess?
WALTON: Huh?
ATTORNEY: Can you take a guess? Do you have any idea?
WALTON: Umm, no. I don’t know.
ATTORNEY: Are you concerned about dying?
WALTON: No.
ATTORNEY: Why not?
WALTON: I don’t know.
ATTORNEY: Do you know what happens when you die?
WALTON: Umm, no, not really. I don’t know. I don’t even know what’s what. You know, I don’t know.
ATTORNEY: Can you take a guess?
WALTON: Umm, I don’t know. You know what I’m saying? I really don’t [290]*290know, you know that? That’s hard. You know what I’m saying? You know what I’m saying? I don’t know. I don’t even know.
ATTORNEY: What’s hard? You said something was hard.
WALTON: Umm, I don’t know. I really — I really don’t know. You know what I’m saying? I really — really don’t know, you know. I’ve been through a lot. You know what I’m saying? You know, I really don’t know, you know, what’s what and stuff. You know what I’m saying? You know what I’m saying?
Also at the July 2003 Ford hearing, Dr. Alan J. Arikian, a prison psychiatrist who saw Walton numerous times in 1999 and 2003, testified on behalf of the Commonwealth. Dr. Arikian opined that Walton is “a mature young man who elected a lifestyle which has been a disappointment to him and has not fulfilled his expectations.” He further testified that Walton “has a full understanding of what’s going on.”
After consideration of all of this testimony, the district court did not feel it could resolve the question of Walton’s competence to be executed. Accordingly, the court held a second hearing on March 3, 2004, at which Dr. Mark Mills, a forensic psychiatrist whom the parties’ experts selected as a neutral expert, testified. Walton III, 306 F.Supp.2d at 599. Prior to that hearing, the court directed Dr. Mills to address two questions: “(1) whether Walton understands that he is to be punished by execution; and (2) whether Walton understands why he is being punished.” At the hearing, the court reiterated: “Any ... questions” other than “whether the petitioner understands that he’s being punished by execution” and “whether the petitioner understands why he is being punished” are “extraneous.... Anything further is simply irrelevant or immaterial.”
In response to this direction, Dr. Mills opined that, given the “focused and ... circumscribed and ... limited” standard the district court had asked him to apply, he believed that Walton was competent to be executed. “[M]y sense is that the standard for execution is sufficiently low that, sadly, Mr. Walton meets that standard. He knows enough to meet the judge’s questions to him.” Dr. Mills also testified, however, that Walton’s condition made it unlikely that Walton would prepare for his death. The district court then concluded, largely on the basis of Dr. Mills’ testimony, that Walton is competent to be executed because he “understands that he is sentenced to die by execution and that he is to be executed for murdering three people.” Walton III, 306 F.Supp.2d at 601.
B.
In Ford, drawing on long-established common law principles, the Supreme Court held that the Eighth Amendment prohibits execution of the insane. 477 U.S. at 406-10, 106 S.Ct. 2595. Although the Ford Court identified some of the components necessary to demonstrate a constitutionally minimum definition of insanity, application of Ford presents challenges because the Court did not define insanity or mandate procedures that courts must follow in determining whether a defendant is insane. The Court left those tasks to the states, and Virginia has yet to enact any definition or procedures of its own. See supra note 2.
Furthermore, the precise legal standard for incompetence under Ford is complicated by the fact that Justice Powell, who cast the fifth and deciding vote in the case, joined only part of the Court’s opinion and wrote separately to explain his view of the “meaning of insanity in this context.” Ford, 477 U.S. at 418, 106 S.Ct. 2595 (Pow[291]*291ell, J., concurring). Thus, the Justices in the majority in Ford issued three opinions: (1) an opinion for the Court joined by the entire majority, including Justice Powell, id. at 401-10, 106 S.Ct. 2595, (2) a plurality opinion not joined by Justice Powell, id. at 410-18, 106 S.Ct. 2595, and (3) Justice Powell’s concurrence, id. at 418-27, 106 S.Ct. 2595.
Based on his reading of these opinions, Walton maintains that the district court misapplied Ford in two respects. Initially, he argues that, contrary to the district court’s determination, for a defendant to be competent to be executed under Ford, he must have an “ability to assist counsel in his own defense.” Brief of Petitioner at 35, 47. In addition, Walton maintains that a necessary component of the Ford inquiry, not undertaken by the district court, is a determination of whether the defendant is capable of preparing for his own death. Id. at 48-50.
1.
With respect to his first argument — that Ford competence requires an “ability to assist counsel in [one’s] own defense”— Walton cites neither the opinion of the Court in Ford nor even the plurality’s opinion. He merely asserts that support for this argument “can be rationally formulated from inferences found in the Ford plurality opinion.” Id. at 35.
We, of course, must look to the opinion of the Court to determine the Ford requirements. That opinion is silent as to whether a defendant must be able to assist his counsel in order to be found competent to be executed. See Ford, 477 U.S. at 401-10, 106 S.Ct. 2595. Moreover, Justice Powell, the fifth vote necessary for a majority, expressly rejected this position in his concurrence. It has “slight merit,” he reasoned, because in modern times, unlike at common law, “the defendant has access to counsel, by constitutional right at trial, and by employment or appointment at other stages of the process whenever the defendant raises substantial claims.” Id. at 420, 106 S.Ct. 2595 (Powell, J., concurring). Because “a defendant must be competent to stand trial, ... the notion that a defendant must be able to assist in his defense is largely provided for.” Id. at 421, 106 S.Ct. 2595 (Powell, J., concurring); see also id. at 421 n. 2, 106 S.Ct. 2595 (Powell, J., concurring).
Thus, even though Justice Powell’s assurance that it is “unlikely indeed that a defendant today could go to his death with knowledge of undiscovered trial error that might set him free,” id. at 420, 106 S.Ct. 2595 (Powell, J., concurring), has since been called into question, see, e.g., 2002 Ill. Governor’s Commission on Capital Punishment Rep., available at http://www.idoe.state.il.us/ccp/ccp/reports/ commission_report/complete_report.pdf, it is clear that Walton’s argument has never garnered a majority of the Court. Indeed, without indicating whether any Member of the Court accepted that position, all that Ford instructs is that one Member decisively rejected it.
Nevertheless, Walton argues that we should hold as a condition of Ford competence that the defendant have a present ability to assist his counsel. Walton relies on, among other authorities, Justice Frankfurter’s dissent in Solesbee v. Balkcom, 339 U.S. 9, 70 S.Ct. 457, 94 L.Ed. 604 (1950), Justice Marshall’s dissent from the Court’s denial of a writ of certiorari in Rector v. Bryant, 501 U.S. 1239, 111 S.Ct. 2872, 115 L.Ed.2d 1038 (1991), and the American Bar Association standard, which states: “A convict is ... incompetent if, as a result of mental illness or mental retardation, the convict lacks sufficient capacity to recognize or understand any fact which might exist which [292]*292would make the punishment unjust or unlawful, or lacks the ability to convey such information to counsel or the court.” ABA Criminal Justice Mental Health Standards Standard 7-5.6 (1989).
Despite this venerable authority, and the fact that several states embrace Walton’s view, e.g., Miss.Code Ann. § 99-19-57 (2000), in the face of the total silence of the Ford Court as to the necessity of the defendant’s “ability to assist counsel in his own defense” and Justice Powell’s decisive concurrence rejecting consideration of this factor, we decline to hold that .in order to find a defendant competent under Ford, a court must find that he has the present ability to assist counsel. We note that every circuit to have considered this argument has similarly rejected it. See Rohan ex rel. v. Woodford, 334 F.3d 803, 809-10 & n. 3, 812 (9th Cir.2003); Coe v. Bell, 209 F.3d 815, 826 (6th Cir.2000); Barnard v. Collins, 13 F.3d 871, 877 & n. 4 (5th Cir.1994).
2.
In contrast to his first argument, however, Walton’s second contention — that Ford demands inquiry into whether the defendant can prepare for his death — is firmly grounded in both the opinion of the Court in Ford and Justice Powell’s concurrence.3
In the opinion of the Court, which. Justice Powell joined, the Supreme Court explained:
[Tjoday, no less than before, we may seriously question the retributive value of executing a person who has no comprehension of why he has been singled out and stripped of his fundamental right to life. Similarly, the natural abhorrence civilized societies feel at killing one who has no capacity to come to grips with his own conscience or deity is still vivid today.
Ford, 477 U.S. at 409, 106 S.Ct. 2595 (citation omitted). In concurrence, Justice Powell emphasized this point:
If the defendant perceives the connection between his crime and his punishment, the retributive goal of the criminal law is satisfied. And only if the defendant is aware that his death is approaching can he prepare himself for his passing. Accordingly, I would hold that the Eighth Amendment forbids the execution only of those who are unaware of the punishment they are about to suffer and why they are to suffer it.
Id. at 422, 106 S.Ct. 2595 (Powell, J., concurring).
Thus, unlike Walton’s first argument, which the Ford Court did not address and Justice Powell, in concurrence, expressly rejected, his second argument finds support in both the opinion of the Ford Court and Justice Powell’s concurrence. Both agree that it is not enough for a court to determine only that a defendant can recognize the cause and effect between his crime and his punishment. Rather, when deciding whether insanity bars a person’s execution, a court must determine whether that person can, in the language of the Ford Court, “comprehen[d] ... why he has been singled out.” Id. at 409, 106 S.Ct. 2595. Or, using Jus[293]*293tice Powell’s formulation, in order to determine whether a person sentenced to death is “unaware of the punishment [he is] about to suffer and why [he is] to suffer it,” a court must consider whether that person is able to “prepare for his passing.” Id. at 422, 106 S.Ct. 2595 (Powell, J., concurring). See also Garrett v. Collins, 951 F.2d 57, 59 (5th Cir.1992) (suggesting that for a defendant’s Ford claim to survive, he must be able to “prepar[e] for his passing,” but upholding state court’s rejection of Collins’ claim).
Tellingly, although the Commonwealth vigorously urges us to affirm the dismissal of Walton’s Ford claim, it does not contend that Ford requires no consideration of a defendant’s ability to prepare for his death. Rather, Virginia merely argues that ‘Walton’s counsel’s belief that Walton must ... ‘prepare’ for his execution as counsel thinks he should ‘prepare’ ... cannot constitute grounds for finding Walton incompetent.” Brief of Respondent at 47. We agree. However, in this case, it is clear from the record that the district court determined that no consideration of an ability to “prepare” for one’s “passing” is necessary under Ford.
In reaching its conclusion that Walton is competent to be executed, the district court believed that Walton’s ability to prepare for his own death was irrelevant. Thus, the district court told Walton’s attorney at the March 2004 evidentiary hearing, “Any ... questions” other than “whether the petitioner understands that he’s being punished by execution” and “whether the petitioner understands why he is being punished” are “extraneous.... Anything further is simply irrelevant or immaterial.” The expert on which the district court relied, Dr. Mills, clearly felt constrained by the limits of the inquiry imposed by the court. Hence Dr. Mills testified, “The problem for me ... is the issues that the judge asked me to consider I think are so focused and so circumscribed and so limited that I have opined ... he meets those limited criteria.”
As demonstrated above, Ford requires more. A person who can only acknowledge, amidst a barrage of incoherent responses, the bare facts that he will be executed and that his crime is the reason why does not meet the standard for competence contemplated either in the opinion of the Ford Court or in Justice Powell’s concurrence.4 Undoubtedly, determining whether a person is competent to be executed is not an exact science. And in light of the high stakes of such a determination, the impulse of the district court to confine the inquiry to the most precise possible standard is understandable, particularly since Virginia has yet to adopt procedures for bringing a Ford claim. But the inquiry required by Ford, “[w]hether its aim be to protect the condemned from fear and pain without comfort of understanding, or to protect the dignity of society itself from [294]*294the barbarity of exacting mindless vengeance,” 477 U.S. at 410, 106 S.Ct. 2595, is broader than the inquiry the district court conducted in this case.5
Accordingly, we vacate the district court’s judgment on Walton’s Ford claim and remand for further proceedings.
III.
We next address Walton’s Atkins claim.
In Atkins I, the Supreme Court held that the Eighth Amendment prohibits execution of the mentally retarded. Atkins I, 536 U.S. at 321, 122 S.Ct. 2242. As in Ford, the Court “ ‘le[ft] to the State[s] the task of developing appropriate ways to enforce the constitutional restriction upon [their] execution of sentences.’” Id. at 317, 122 S.Ct. 2242 (quoting Ford, 477 U.S. at 416-17, 106 S.Ct. 2595) (second and third alterations in original).
Unlike in the case of insanity, however, see supra note 2, the Virginia legislature moved quickly in the wake of the Supreme Court’s decision in Atkins I to establish procedures for regulating execution of the mentally retarded. See Atkins v. Commonwealth, 266 Va. 73, 581 S.E.2d 514 (2003) (“Atkins II”). Among the newly enacted Virginia provisions is a definition of mental retardation:
“Mentally retarded ” means a disability, originating before the age of 18 years, characterized concurrently by (i) significantly subaverage intellectual functioning as demonstrated by performance on a standardized measure of intellectual functioning administered in conformity with accepted professional practice, that is at least two standard deviations below the mean and (ii) significant limitations in adaptive behavior as expressed in conceptual, social and practical adaptive skills.
Va.Code Ann. § 19.2-264.3:1.1(A) (Michie 2004); cf. Atkins I, 536 U.S. at 308 n. 3, 318, 122 S.Ct. 2242 (noting that “clinical definitions of mental retardation require” both “subaverage intellectual functioning” and “significant limitations in adaptive skills”).
The Supreme Court of Virginia has held that “[pjerformance on a standardized measure of intellectual functioning ... at least two standard deviations below the mean” corresponds to an IQ score of 70 or below. See Johnson v. Commonwealth, 267 Va. 53, 591 S.E.2d 47, 59 (2004); see also American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders 39 (4th ed.1994) (hereinafter “DSM IV”).6 The defendant bears the bur[295]*295den of proving that he is mentally retarded by a preponderance of the evidence. Ya. Code Ann. § 19.2-264.8:1.1(0.
Thus, for a defendant to be considered mentally retarded under Virginia law, he must have “significantly subaverage intellectual functioning” and “significant limitations in adaptive behavior” (as statutorily defined), and both must originate before age 18.
The procedural posture of Walton’s Atkins claim is very similar to the one we recently addressed in Walker v. True, 399 F.3d 315 (4th Cir.2005). Like Walker, Walton’s conviction and sentence became final before the Supreme Court issued its opinion in Atkins I. Like Walker, because Walton completed his direct appeal and state habeas proceedings before he could raise his Atkins claim, “his sole remedy” under Virginia law “lie[s] in federal court.” Va.Code Ann. § 8.01-654.2 (Michie 2000 & Supp.2004). Therefore, as in Walker, when considering Walton’s habeas petition, the district court faced no state factual findings owed deference and, accordingly, “was obliged to assume all facts pleaded by [Walton] to be true” in resolving the Government’s motion to dismiss the Atkins claim. Walker, 399 F.3d at 319 (internal quotation marks and citation omitted). But, as in Walker, the district court in the case at hand failed to do so.
Rather than assume the truth of the facts alleged in Walton’s petition, the district court rejected Walton’s Atkins claim because it found that Walton had “not forecast sufficient evidence to show that his alleged subaverage intellectual functioning originated before he was 18 years of age.” Walton II, 269 F.Supp.2d at 700. On appeal in this case, echoing its words in Walker, the Commonwealth acknowledges that the district court’s order “dismissing” Walton’s claim was actually “in the nature of a grant of summary judgment.” Compare Brief of Respondent in Walker at 14 with Brief of Respondent in Walton at 22. But even if summary judgment was the correct procedure, which it was not, see Walker, 399 F.3d at 319 & n. 1, the district court’s ruling cannot stand because, as in Walker, the court resolved a factual dispute in favor of the Government. See id. at 319.
In rejecting Walton’s Atkins claim, the district court relied on the results of two IQ tests administered to Walton around the time of his eighteenth birthday. The first, a WAIS-R administered to Walton at age seventeen years and eight months, purportedly gave him a full-scale IQ of 90, Walton II, 269 F.Supp.2d at 694-95; the second, a WAIS-R administered to Walton at age eighteen years and five months, gave him a full-scale IQ of 77. Id. at 695. Walton alleges that neither score bars his claim, and that the score of 77 in fact supports it.
Specifically, with respect to the first IQ test, Walton maintains that there is “no way to determine the validity of that test” since Virginia has put forth no “raw data” from it. He contends that this first test “is not a test at all,” but rather:
a juvenile intake report which refers to scores on a purported test. There is no information about who administered the test, when it was administered, or what the testing conditions were when the test was given. There is no raw data for the test and no indication what protocols were to be followed and whether the [296]*296standardized format of the test was adhered to in full or what accommodations or adjustments were made.
Brief of Petitioner at 61; cf. Walker, 399 F.3d at 323 (discussing petitioner’s allegation that one of his IQ tests is“ ‘highly unreliable for multiple reasons’ ”). If Walton can show that the IQ test he took when he was seventeen was not “administered in conformity with accepted professional practice,” then, under Virginia law, it cannot be used to refute his alleged mental retardation. See Va.Code Ann. § 19.2-264.3:1.1(A).
Regarding the second test, Walton argues (much as Walker did with respect to an IQ score of 76) that when adjusted for the “Flynn Effect” and the standard margin of error, his score of 77 actually supports his claim of mental retardation. Pursuant to the Flynn Effect, according to Walton, “as the age of an intelligence test moves farther from the date on which it is normed, the mean score of the population as a whole on that test increases.” Reply Brief at 25. And, adjusted for the Flynn Effect, he contends, his IQ score of 77 “indicates a full-scale score of 74.” Brief of Petitioner at 61. Ordinarily, of course, a score of 74 would not put Walton within the legal range of mental retardation in Virginia. But, like Walker, he further maintains that, after accounting for the standard five-point margin of error, his score of 74 falls within the required range. See Reply Brief at 21, 25-26 & n.ll; see also DSM IV at 39 (“It should be noted that there is a measurement error of approximately 5 points in assessing IQ....”).7
Because the district court failed to consider Walton’s contention as to the inadequacy of the first IQ test and the impact of the Flynn Effect or the standard margin of error on the second test, we must, as in Walker, vacate and remand for further proceedings.8 On remand, the district court should determine the adequacy of the first test and the persuasiveness of Walton’s Flynn Effect evidence as to the second test; if the court finds the Flynn Effect evidence persuasive, it should then determine whether the Virginia statute permits “consideration of measurement error in order to determine whether” Walton’s purported score of 74 is “ ‘two stan[297]*297dard deviations below the mean.’ ” Walker, 399 F.3d at 323.
Walton also submitted evidence of two more recent IQ tests, both reporting scores below the cutoff for mental retardation. See Walton II, 269 F.Supp.2d at 695 (noting August 9, 1999 WAIS-R reporting full-scale IQ of 69 and May 2003 GAMA reporting full-scale IQ of 66). We note that under the Virginia statute, “[ajssessment of developmental origin shall be based on multiple sources of information generally accepted by the field of psychological testing and appropriate for the particular defendant being assessed, including, whenever available, educational, social service, medical records, prior disability assessments, parental or caregiver reports, and other collateral data.” Va.Code Ann. § 19.2-264.3:1.1(B)(3). Thus, on remand, the district court may properly consider the scores from these tests, even though they were administered well after Walton’s eighteenth birthday. Cf. Walker, 399 F.3d at 323 n. 7.9
On remand the district court may have to consider Walton’s “limitations in adaptive behavior” before age eighteen— another essential element of his claim. Because the court rejected Walton’s Atkins claim due to his asserted failure to proffer sufficient evidence of mental retardation, the district court did not reach any conclusions as to this element. We note only that, as required by statute, Walton has set out a number of facts, which, if credited, tend to indicate significant limitations in adaptive behavior.
Walton would ordinarily not be entitled to an evidentiary hearing on remand because he has “failed to develop the factual basis of [his Atkins ] claim in State court.” 28 U.S.C. § 2254(e)(2)(2000). But because Atkins was decided after the denial of his direct appeal and state habeas petition became final, he cannot be held accountable for failure to raise this claim in state court. See Va.Code Ann. § 8.01-654.2 (providing that the “sole remedy” for people in Walton’s position, who have “completed both a direct appeal and a habeas corpus proceeding” under Virginia law, “lie[s] in federal court”); Walker, 399 F.3d at 319, 326-27.
At the evidentiary hearing held on remand, the parties will have the opportunity to demonstrate the reliability vel non of Walton’s first IQ test and the persuasiveness of other possible mental retardation evidence, including evidence as to the Flynn Effect, measurement error, other IQ tests, and adaptive behavior. We make no determination as to the validity of Walton’s arguments on any of these points; we hold merely that Walton is entitled to be heard on them.
IV.
For the reasons set forth above, we vacate the judgment of the district court [298]*298and remand for further proceedings consistent with this opinion.
VACATED AND REMANDED.