Gary Chad Thomason is a burglar who shot and killed the homeowner who came upon him while he was burglarizing the victim’s home. In a bench trial, he was convicted of malice murder, burglary, and possession of a firearm by a convicted felon, and was sentenced to death. After affirmance by this Court of that conviction and sentence (Thomason v. State, 268 Ga. 298 (486 SE2d 861) (1997)), he filed a petition for a writ of habeas corpus. His petition was denied on all grounds save one — that he was not afforded the effective assistance of counsel during the sentencing phase of his bench trial because trial counsel failed to investigate Thomason’s background *435adequately and failed to present an effective case in mitigation. As a result of the determination that Thomason received ineffective assistance of counsel during the sentencing phase, the habeas court ordered a new sentencing trial. The warden appeals that ruling in Case No. S02A1515, and Thomason cross-appeals in Case No. S02X1516 the habeas court’s rejection of his other claims of constitutional error.
Case No. S02A1515
1. In granting relief, the habeas court noted that the mitigation evidence offered at trial consisted only of Thomason’s profession of remorse, his lack of violent tendencies, testimony that he was easily influenced and was always with someone else when he got in trouble, and his mother’s mention of his hospitalization at Charter Peachford Hospital for marijuana usage. The habeas court then chronicled the mitigation evidence trial counsel had and did not use1 and the mitigation evidence trial counsel did not have but which was “readily obtainable through reasonable diligence.”2 The habeas court noted that trial counsel had testified at the hearing that the background information was not used or pursued because they believed it could not be used effectively without an expert and the trial court had denied their request for additional funding for a psychological evaluation. The habeas court found that counsel had not been reasonably diligent in their pursuit of expert assistance, had substantially abandoned Thomason’s mitigation case, had unreasonably failed to make *436use of considerable information in counsel’s possession, made no effort to secure other information readily available, and made no effort to pursue alternative possibilities for securing assistance from the psychiatrist who examined Thomason. Based on those findings, the habeas court found counsel’s performance deficient, and further concluded that there was a reasonable probability that the death penalty would not have been imposed if counsel had effectively utilized the available information and resources.
A habeas court’s determination on a claim of ineffective assistance of counsel is to be affirmed unless the reviewing court concludes the habeas court’s factual findings are clearly erroneous or are legally insufficient to show ineffective assistance of counsel. See Head v. Carr, 273 Ga. 613, 616 (544 SE2d 409) (2001). Review of the record in this case persuades us that there is evidence to support the trial court’s findings and that they are not, therefore, clearly erroneous. It remains our task to consider whether those facts support the legal conclusion that counsel were ineffective and that the ineffectiveness prejudiced Thomason. Id.
Mitigating evidence, “anything that might persuade the jury to impose a sentence less than death,” (Head v. Ferrell, 274 Ga. 399, 405 (554 SE2d 155) (2001)), is critical in the sentencing phase of a death penalty trial since “the [jury] may withhold [imposition of] the death penalty for any reason, or without any reason.” Smith v. Francis, 253 Ga. 782, 787 (325 SE2d 362) (1985). We have recognized the importance of mitigating evidence by holding that the permissible scope of such evidence is wide (Barnes v. State, 269 Ga. 345 (27) (496 SE2d 674) (1998)), and by noting that evidentiary rules are relaxed during the sentencing phase. Smith v. State, 270 Ga. 240 (12) (510 SE2d 1) (1998). The test for finding deficient performance of an attorney who is claimed to have been ineffective with regard to mitigating evidence is whether a reasonable lawyer would have acted the way defense counsel did. Head v. Carr, supra, 273 Ga. at 616. An attorney’s failure to have a mental health expert review medical records for mitigating evidence can be unreasonable conduct. Turpin v. Lipham, 270 Ga. 208, 216 (510 SE2d 32) (1999). In the case at bar, defense counsel knew of two mental health experts who had spent time with Thomason — one a clinical psychologist who testified at the defendant’s competency hearing that the defendant has an IQ of 77, and the other a psychiatrist who interviewed the defendant, who told defense counsel he saw in the defendant indications of intellectual impairment, low self-esteem, and depression, to whom defense counsel offered the defendant’s school, medical, and institutional records as well as information about the crime for a forensic evaluation, but to whom the attorney never gave the offered material. In addition to failing to follow through on his promise to give the requested mate*437rial to the psychiatrist, defense counsel called neither expert to present evidence in mitigation — and then presented none of the mitigating evidence the defense had amassed because counsel did not know how to do it without an expert.
Trial counsel recognized the need for expert testimony, yet failed to have the expert who had already conducted an interview with the defendant execute an affidavit for use in securing additional funding for the expert. Instead, trial counsel asked the expert for a letter breaking down the cost of a full forensic psychiatric evaluation of Thomason. The expert’s letter apparently served as the basis for trial counsel’s request for an additional $25,000 for mental health expert assistance. When trial counsel’s efforts to obtain the additional funding were rejected by the trial court, trial counsel never contacted the expert again. In an affidavit submitted at the habeas hearing and relied on by the habeas court, the expert stated he would have worked with counsel without further funding or for a figure significantly less than that set forth in his letter had that been necessary. The expert noted he could have reduced the cost by utilizing defense team members to conduct interviews rather than conducting them himself and, had he had the materials provided to him by habeas counsel, he would have been able to assist in providing evidence in mitigation. However, trial counsel never contacted the expert again once the request for additional funding was denied. We conclude, given the importance of mitigating evidence in death penalty cases, that an attorney has not acted reasonably when he fails to call mental health experts he knows have mitigating evidence and explains his failure to present lay mitigating evidence by asserting that he had no experts to call.
It is likely that trial counsel’s guard was down at the sentencing phase due to counsel’s belief that the trial judge who presided over the bench trial would not impose a death sentence.3 While we agree with the habeas court’s determination that trial counsel’s advice to Thomason to waive his right to a jury trial based on counsel’s erroneous assumptions about the trial judge did not alone amount to ineffective assistance of counsel, we conclude that counsel’s erroneous *438assumptions and the concomitant feeling of assuredness caused counsel to be less diligent in preparing for the sentencing phase than they would have had they believed they were dealing with a factfinder who might impose the death penalty.
These circumstances, coupled with counsel’s failure to make use of the mitigating evidence and the experts they had, persuade us that the habeas court was correct in its conclusion that there is a reasonable probability that the presentation of the mitigating evidence presented at the habeas hearing would have changed the outcome of the sentencing phase of Thomason’s trial. See Head v. Carr, supra, 273 Ga. at 626. Accordingly, we affirm the grant of a new sentencing trial.
Case No. S02X1516
2. In any case in which doubt arises concerning this Court’s jurisdiction, we have a duty to address that question. Powell v. City of Snellville, 275 Ga. 207 (1) (563 SE2d 860) (2002). In the present case, the dissent asserts that the cross-appeal should be dismissed because Thomason did not file his notice of cross-appeal within 15 days of the service on him of the notice of appeal as is required by OCGA § 5-6-38. In fact, Thomason filed his notice of cross-appeal 17 days after service by mail of the warden’s notice of appeal.
The dissent is correct in noting that OCGA § 9-14-52 (a) provides that appeals in habeas corpus cases shall be governed by the Appellate Practice Act, OCGA § 5-6-30 et seq. However, that provision only means that appeals in habeas corpus cases, once begun, are to be handled in the same way as other civil appeals. The Appellate Practice Act does not provide for every single act involved in an appeal. Because there is no provision in the Appellate Practice Act for computing time limits, the Court of Appeals has at least twice found it necessary to supplement the provisions of the Appellate Practice Act by reference to OCGA § 9-11-6: Southern Guar. Ins. Co. of Ga. v. Goddard, 190 Ga. App. 97, 98 (378 SE2d 130) (1989) (applying OCGA § 9-11-6 (a) to the computation of the time for filing a notice of appeal); Nat. Consultants v. Burt, 186 Ga. App. 27 (1) (366 SE2d 344) (1988) (applying the provision in OCGA § 9-11-6 (e) for three extra days when a notice is served by mail to the computation of time for filing a cross-appeal). Application of those provisions to situations not provided for in the Appellate Practice Act is consistent with the General Assembly’s command in OCGA § 5-6-30 that the Appellate Practice Act “shall be liberally construed so as to bring about a decision on the merits of every case appealed and to avoid dismissal of any case. . . .” We believe the approach of the Court of Appeals in the cases cited above is appropriate for the present case and hold that *439the notice of cross-appeal was timely because it was served within the fifteen-day period provided by OCGA § 5-6-38 (a) plus the three-day extension provided for in OCGA § 9-11-6 (e).
3. To the extent that Thomason’s cross-appeal arguments address matters relevant solely to his death sentence, they are moot in light of our affirmance in the main appeal. Accordingly, those arguments will not be discussed here.
4. Thomason contends his trial counsel rendered ineffective assistance by advising him to waive a jury trial. The habeas court found as fact that trial counsel had a number of strategic reasons to favor a bench trial, including a belief that a judge would think Thomason’s crimes less worthy of death than a jury, a perception that the trial judge personally disliked the district attorney for various reasons, a perception that the trial judge was annoyed with the district attorney’s conduct during plea discussions, and a fear of the impact the victim’s family in the courtroom would have on a jury. The habeas court also found as fact, however, that one of counsel’s reasons for preferring a bench trial, a belief the trial judge had never sought the death penalty during his former tenure as a district attorney, was incorrect. The habeas court, after finding these facts, did not decide as a matter of law whether counsel had performed unreasonably in recommending Thomason waive his right to a jury trial, but proceeded directly to the second prong of the test set out in Strickland v. Washington, 466 U. S. 668 (III) (104 SC 2052, 80 LE2d 674) (1984), and found no prejudice. However, pursuant to the rule that this Court must accept the habeas court’s findings of fact unless they are clearly erroneous, but applies those facts to the law de novo (Head v. Carr, supra, 273 Ga. at 616), we conclude as a matter of law that counsel’s advice to Thomason to waive a jury trial was not deficient performance, even in light of their one mistaken reason for giving that advice. Whether to waive a jury trial is a strategic decision to be made by an accused after consultation with counsel. Van Alstine v. State, 263 Ga. 1, 2 (426 SE2d 360) (1993). Strategic decisions of counsel (in this case, whether to advise Thomason to waive a jury trial) are to be judged by “whether the decision was . . . reasonable on the basis of the facts of the particular case, viewed as of the time of counsel’s conduct. [Cits.]” Battles v. Chapman, 269 Ga. 702, 704 (1) (a) (506 SE2d 838) (1998). Applying that standard to the facts found by the habeas court, we conclude the other reasons for advising Thomason to waive jury trial constituted reasonable bases for that strategic decision. Accordingly, we find no fault in the habeas court’s holding that giving that advice did not constitute ineffective assistance of counsel.
5. The habeas court rejected Thomason’s contention that counsel were ineffective in their conduct of the plea bargain process. That *440court’s findings accurately reflect the fact that, despite Thomason’s inconsistent reporting of the facts to counsel and his unwillingness to accept a sentence of life without parole, counsel actively pursued opportunities to seek a plea agreement with the State. Counsel discussed the sentencing and plea possibilities with Thomason and diligently pursued information that would assist Thomason in obtaining an acceptable plea agreement. In light of counsel’s efforts, we find no merit in Thomason’s contention that his trial counsel rendered deficient performance in assisting and advising him in the plea bargaining process. Strickland v. Washington, supra, 466 U. S. at 687; Smith v. Francis, supra, 253 Ga. at 783-784 (1).
6. Thomason has failed to demonstrate that his trial counsel rendered deficient performance in seeking funds for a crime scene reconstruction expert, and, furthermore, even assuming counsel performed deficiently, Thomason has failed to show prejudice relevant to his convictions, as the testimony presented by Thomason’s investigator in the habeas court fails to cast doubt on Thomason’s guilt. Id.
7. Thomason argues that his written and oral waiver of a jury trial was not knowing, intelligent, and voluntary. As an independent claim, this argument is barred by procedural default, because it was not raised on direct appeal. Head v. Ferrell, 274 Ga. at 401-402 (III). However, Thomason also argues that his counsel rendered ineffective assistance in failing to raise the claim on direct appeal, which, if proven, would serve both as cause to set aside the procedural bar and as an independent claim. Id. Nevertheless, our review of the record fails to support Thomason’s contention that the trial court acted improperly or misleadingly with regard to plea discussions or the waiver of a jury trial, that the decision to recommend the waiver was made without proper consultation with Thomason, or that Thomason was unable to understand the advice of his counsel and the warnings of the trial court. See Watson v. State, 274 Ga. 689, 690-691 (2) (558 SE2d 704) (2002) (“A trial court should ask the defendant sufficient questions on the record so that the court can ensure the defendant’s waiver is knowing, voluntary, and intelligent.”); Grant v. State, 246 Ga. App. 376, 377 (3) (540 SE2d 634) (2000) (discussing appropriate role of trial court during the parties’ plea discussions and in accepting a waiver of jury trial). Because Thomason’s underlying claim that his waiver was not knowing, intelligent, and voluntary lacks merit, it must also follow that Thomason’s appellate counsel did not render ineffective assistance in not raising the claim on direct appeal and, in turn, that there is no cause to set aside the procedural bar to the underlying claim. Battles v. Chapman, supra, 269 Ga. at 703-705 (setting forth standard for examining appellate counsel’s performance).
8. This Court found on direct appeal that the evidence was suffi*441cient to prove beyond a reasonable doubt that Thomason was guilty of malice murder. 09999999999999999999999999999999999999999990Thomason v. State, 268 Ga. 298 (1) (486 SE2d 861) (1997). The habeas court properly found this Court’s assessment of the trial evidence to be res judicata. Head v. Ferrell, 274 Ga. at 401 (II). The habeas court also did not err in concluding that Thomason had not shown new evidence capable of supporting his claim of a miscarriage of justice. See OCGA § 9-14-48 (d); Valenzuela v. Newsome, 253 Ga. 793, 796 (4) (325 SE2d 370) (1985).
9. The habeas court correctly found Thomason’s claim of alleged evidence suppression by the State was barred by procedural default because it was not raised on direct appeal. Head v. Ferrell, 274 Ga. at 401-402 (III). We find the habeas court did not err in not finding sufficient cause and prejudice to set aside the procedural bar to this claim, particularly with respect to the claim’s relation to Thomason’s convictions. Id. See Brady v. Maryland, 373 U. S. 83 (83 SC 1194, 10 LE2d 215) (1963).
10. The habeas court properly found Thomason’s claim regarding the Unified Appeal Procedure was barred by procedural default and no cause or prejudice had been shown to set aside that bar. Head v. Ferrell, 274 Ga. at 401-402 (III). See Jackson v. State, 270 Ga. 494, 498-499 (10) (512 SE2d 241) (1999).
11. The habeas court properly found Thomason’s claim regarding cumulative error, which is not recognized in Georgia courts, was barred by procedural default and no cause or prejudice had been shown to overcome that bar. Head v. Ferrell, 274 Ga. at 401-402 (III). See Laney v. State, 271 Ga. 194 (11) (515 SE2d 610) (1999).
12. The habeas court correctly found Thomason’s claim he was tried while incompetent was barred by procedural default and no cause or prejudice had been shown to overcome that bar. Head v. Ferrell, 274 Ga. at 401-402 (III).
13. The habeas court correctly found Thomason’s claim regarding his being called as a witness by the State in his competency trial was barred by procedural default. Id. The habeas court did not err in not finding Thomason had demonstrated prejudice, either with respect to the cause and prejudice test applicable to claims barred by procedural default or with respect to Thomason’s related ineffective assistance of trial counsel claim. Id. See Strickland v. Washington, supra, 466 U. S. at 687 (III). Accordingly, we need not address the underlying merits of Thomason’s claim he was improperly called as a witness at his competency trial.
14. The habeas court correctly found Thomason’s unspecific claim regarding his alleged absence during portions of his trial was barred by procedural default and Thomason had failed to show cause or prejudice sufficient to set aside that bar. Head v. Ferrell, supra, 274 Ga. at 401-402 (III).
*44215. The habeas court correctly found Thomason’s claim he was denied sufficient assistance from a mental health expert is barred as res judicata because that same claim was rejected by this Court on direct appeal. Head v. Ferrell, supra, 274 Ga. at 401 (II). See Thomason v. State, supra, 268 Ga. at 310-311 (7).
16. The trial court correctly found Thomason’s claim of alleged misconduct by his competency trial jurors was barred by procedural default and Thomason had failed to show cause and prejudice sufficient to set aside that bar. Head v. Ferrell, 274 Ga. at 401-402 (III).
Judgment affirmed in Case No. S02A1515.
All the Justices concur, except Hunstein, Carley and Thompson, JJ, who dissent. Judgment affirmed in Case No. S02X1516. All the Justices concur, except Sears, P. J., and Thompson, J., who dissent.Trial counsel had, but did not use, documentation of Thomason’s learning disabilities; teacher referrals for psychiatric assessment; a three-month hospitalization at Charter Peachford with diagnoses of major depressive disorder, marijuana dependence, and amphetamine abuse; the clinical psychologist who had testified at Thomason’s competency hearing that his IQ was 77, a score that indicated borderline mental functioning; a professional diagnosis that Thomason’s parents were enablers and that Thomason had feelings of insecurity, low self-esteem, and inferiority; a clinical social worker’s opinion that Thomason’s family had a strong genetic disposition to alcohol and drug abuse; and that Thomason had dropped out of school after completing the seventh grade and had a history of suicidal ideations and possible suicide attempts.
At the habeas hearing, Thomason’s elementary school principal, who was called as a witness in the sentencing phase only to authenticate school records, recounted an elementary school incident involving Thomason and his father’s reaction to school officials’ concerns about Thomason’s behavior. The habeas court admitted an affidavit from Thomason’s uncle, who testified during the sentencing phase that Thomason was a passive child, in which affidavit the uncle tells of Thomason’s drug usage at a young age and of the rape and abuse Thomason suffered in prison. Thomason’s only sibling and several elementary school teachers who were not contacted by trial counsel testified at the habeas hearing or executed affidavits about their personal knowledge of Thomason and his circumstances. Medical records other than the Charter Peachford hospitalization and school assessments were not obtained, even though one indicated Thomason had suffered a febrile convulsion as an infant, and a treating physician stated in an affidavit that he recalled treating Thomason 26 years earlier because “he seemed particularly slow” and the physician feared he was mentally retarded.
On. advice of counsel, Thomason waived his right to a jury trial. Counsel believed the case was not a death penalty case and that a judge would see that more clearly than a jury, especially in light of the constant courtroom presence of the victim’s family, who were influential members of the community. Counsel also believed (albeit wrongly) that the judge before whom the case was tried had never sought the death penalty while serving as district attorney; that the judge disliked the current district attorney because the latter had opposed and defeated the judge in an election for district attorney; and that the judge believed the case called for life imprisonment since the judge had expressed displeasure with the district attorney for deferring to the victim’s family while negotiating a plea agreement for life imprisonment.