Milton Rene Couch appeals in forma pauperis the district court’s 1 dismissal of his petition for a writ of habeas corpus *1339under 28 U.S.C. § 2254 (1966). Couch contends that the district court erred in concluding that trial counsel was not ineffective for failing to pursue a trial defense of lack of capacity due to mental illness.2 We find the district court properly concluded that intoxication without psychosis did not constitute a “mental disease or defect” amounting to mental illness in mitigation of criminal responsibility within the meaning of the Missouri Mental Responsibility Act, Mo.Rev.Stat. §§ 552.010-552.020 (1969) and affirm the dismissal of Couch’s petition.
I.
On October 5, 1976, Couch was convicted of first degree murder3 and sentenced to life imprisonment in St. Louis County, Missouri. The Missouri Court of Appeals affirmed the conviction. State v. Couch, 567 S.W.2d 360 (Mo.App.1978). Couch moved for post-conviction relief, pursuant to Missouri Supreme Court Rule 27.26,4 on the ground that trial counsel’s failure to pursue a mental illness defense constituted ineffective assistance. The St. Louis circuit court denied the motion after an evi-dentiary hearing. The Missouri Court of Appeals affirmed the circuit court’s eviden-tiary and legal conclusions made in the collateral proceeding.5
In the instant case, Couch petitioned the district court pro se for a writ of habeas corpus, pursuant to 28 U.S.C. § 2254, alleging ineffective assistance of counsel in violation of the sixth amendment. Couch claimed that trial counsel failed to (1) adequately investigate a potential “mental disease or defect,” the discovery of which would have negated Couch’s capacity to stand trial, and (2) failed to interview prosecution witnesses. The district court adopted the magistrate’s report and recommendation,6 dismissed the petition and denied Couch’s motions for a certificate of probable cause and appointment of counsel.7 On Couch’s initial appeal, we ordered the district court to make an evidentiary record8 regarding trial counsel’s investigation of potential defenses, since the circumstances involved intoxication that might have negated the specific intent necessary *1340for a conviction on a charge of first degree murder. We then granted Couch’s application for a certificate of probable cause on the basis of facts, initially tending to support the ineffectiveness of counsel claim, found by Magistrate Jackson at the eviden-tiary hearing. However, we now affirm the district court’s dismissal of Couch’s petition for habeas corpus relief.
II.
Couch entered a bar in St. Louis, Missouri, on the afternoon of May 2, 1975, acted irrationally and drank excessively. Couch left the bar and returned around 8:00 p.m. While continuing to drink excessively, Couch engaged Rose Winn, a female patron, in a conversation. Couch repeatedly bumped into Charles Adams, who was seated on an adjacent barstool. Adams offered Couch his seat. Couch stared at him for several minutes. Then, in an attempt to divert Winn’s attention, he bought her a drink. Couch pulled a gun, placed it next to Adams’ head, and fired, fatally wounding Adams. Couch then fled.
On May 7, 1975, Couch was committed to the Veterans Administration Medical Center. When interviewed, Couch recounted a history of amnesia due to acute intoxication. Couch claimed not to remember the events of May 2, but indicated that he did not believe he could have killed Adams because he was in a hospital at the time of the shooting visiting his ailing wife. Couch admitted a drinking problem. The staff psychiatrist concluded9 that Couch suffered from acute brain syndrome associated with alcohol intoxication and amnesia as a direct result, but was not psychotic.
On August 7, 1975, the St. Louis circuit court ordered Couch, pursuant to Mo.Rev. Stat. § 552.020 (1971),10 to be admitted to the Maximum Security Unit of Fulton State Hospital to undergo a pretrial psychiatric evaluation to determine his capacity to stand trial. Couch was interviewed by a psychiatrist on August 12, 1975. The psychiatrist observed no obvious signs of mental disturbance or thought disorder, no inappropriateness of mood, orientation intact in all spheres, memory for both recent and remote events and no hallucinations or delusions. Couch denied responsibility for the offense charged but admitted to suffering from a manic-depressive condition which he directly attributed to a drinking problem. Couch indicated that he knew murder was wrong and punishable and, significantly, claimed to be able to control his conduct. Tests did not indicate any perceptual or motor abnormalities but did reveal a manipulative personality. Nursing notes supported a determination of a “very” good mental state. The psychiatrist diagnosed “no mental disorder.”11 *1341The Fulton study was filed with the trial court indicating that “no mental disease or defect” existed. Original trial counsel did not object to the study within the statutorily prescribed period.12 Therefore, since Couch was deemed capable of standing trial, the case was listed on the trial calendar.
Trial counsel consulted with Couch. Couch never contended that he suffered from psychosis as a result of alcoholism. In light of this fact and the fact that original trial counsel did not object to the Fulton study within the statutory period, trial counsel did not undertake to further investigate a mental illness lack of capacity defense based on “mental disease or defect.” Trial counsel testified at the evidentiary hearing that in normal course, if a psychiatric report concluded that a defendant had no “mental disease or defect,” was not psychotic, and was therefore deemed capable of standing trial, no follow-up would be undertaken unless the defendant exhibited obvious signs of mental disturbance.
III.
Couch contends that he was denied effective assistance of counsel in violation of the sixth amendment. Specifically, Couch alleges that counsel failed to (1) properly investigate and assert the statutory mental illness defense of “mental disease or defect,” pursuant to Mo.Rev.Stat. § 552.010 (1969), (2) interview prosecution witnesses, and (3) assert intoxication as a mitigating factor affecting the degree of culpability, and asserted a “ludicrous” alibi defense.
Ineffective assistance of counsel is a mixed question of fact and law.13 This court must independently review the district court’s legal conclusions when considering an appeal in a habeas corpus proceeding. Laws v. Armontrout, 863 F.2d 1377, 1381 (8th Cir.1988) (en banc). However, the district court’s findings of fact are only reviewable under the clearly erroneous standard. Additionally, a state court’s specific factual findings made in the course of deciding an ineffectiveness of counsel claim are presumed correct pursuant to 28 U.S.C. § 2254(d). See Sumner v. Mata, 449 U.S. 539, 101 S.Ct. 764, 66 L.Ed.2d 722 (1981).
Couch was charged with fatally shooting Adams in a bar. He was intoxicated at the time. In 1975, “mental disease or defect” constituted a mental illness which gave rise to a lack of capacity defense to criminal culpability in Missouri. “Mental disease or defect” was defined as a “congenital and traumatic mental condition as well as disease,” but specifically excluded “alcoholism without psychosis.” Mo.Rev.Stat. § 552.010 (1969). Therefore, intoxication or drugged condition was not a defense in mitigation of criminal responsibility.14
*1342The Fulton study found that Couch had no “mental disease or defect” within the meaning of § 552.010, knew and appreciated the nature, quality and wrongfulness of his alleged conduct and was capable of conforming his conduct to the requirements of law. The Fulton study incorporated by reference a medical report from the Veterans Hospital compiled seven days after the shooting. The VA Hospital report diagnosed Couch as suffering from acute brain syndrome associated with alcohol intoxication, accompanied by amnesia. The report concluded that Couch was not psychotic but was an alcoholic who suffered from sociopathic traits and anxiety symptoms. On September 26, 1975, Couch received a copy of the Fulton study. Trial commenced October 4, 1976.
Couch first argues on appeal that trial counsel was ineffective for failing to pursue a mental illness defense (i.e., lack of capacity to stand trial) based on “mental disease or defect.” In Laws v. Armontr-out, this court, en banc, concluded that trial counsel had conducted an adequate investigation into a possible mental illness defense, since the clinical evidence did not support a conclusion that a “mental disease or defect” existed.15 The Laws court adopted the legal conclusions of the Missouri Court of Appeals on Laws’ Rule 27.26 motion based on the state court’s specific findings of fact.16 Couch appealed from denial of his Rule 27.26 motion. The Missouri Court of Appeals undertook a Laws approach and concluded that the evidentia-ry record from the Rule 27.26 hearing did not support Couch’s claim of ineffective assistance of counsel for failure to assert a mental illness defense based on “mental disease or defect.” 17
Couch did not suffer from a congenital or traumatic mental condition or disease. Couch never indicated to counsel that he suffered from psychosis as a result of alcoholism. Evidentiary Hearing Transcript at 16. Couch claimed to suffer from amnesia regarding the event attributed to voluntary intoxication. A claim of amnesia precipitated by voluntary intoxication after the fact is not sufficient evidence that the intoxication negated specific intent at the time of the shooting or rendered Couch involuntarily incapable of conforming his conduct to the requirements of law. The statutory intoxication or drugged condition defense did not exist. Couch’s intoxicated state did not negate the necessary elements of deliberateness or premeditation. The record shows that Couch fixated on Adams for several minutes, then deliberately drew Winn’s attention away by offering to buy her a drink, and then executed Adams in cold blood.
IV.
The Supreme Court in Strickland v. Washington, 466 U.S. 668, 104 S.Ct. 2052, 80 L.Ed.2d 674 (1984), articulated a two prong standard, which a petitioner must meet to prevail on an ineffective assistance of counsel claim seeking habeas corpus re*1343lief. Under Strickland, a petitioner has the burden of proving that counsel’s performance was not only deficient but that it prejudiced the defense to the extent of a deprivation of a fair trial. Id. at 687, 104 S.Ct. at 2064. A reasonable probability must exist that, but for counsel’s unprofessional errors, the result would have been different.18 This court applied the Strickland standard in Blackmon v. Armontrout, 875 F.2d 164 (8th Cir.1989).
In order for counsel’s performance to be “deficient” within the meaning of Strickland, conduct must fall below an objective standard of reasonableness.19 In this area of inquiry, judicial scrutiny is highly deferential.20 A strong presumption exists in counsel’s favor.21 When determining reasonableness, this court must view conduct from the perspective of counsel at the time of the alleged ineffective assistance.22
Strickland also dictates that any deficiencies in counsel’s performance be prejudicial to the defense so that the outcome of the proceedings cannot be relied on. Id. 466 U.S. at 692, 104 S.Ct. at 2067. An actual adverse effect on the defense is necessary. Id. at 693, 104 S.Ct. at 2067. Courts should determine prejudice on a case by case basis.
A review of the record23 would not have suggested to counsel that Couch was psychotic. Alcoholism without psychosis was *1344specifically excluded from the statutory definition of “mental disease or defect” and could not form the basis of a mental illness defense to criminal conduct. Couch’s condition was not envisioned by § 552.010 as indicative of a lack of capacity to stand trial. Therefore, trial counsel’s performance was not deficient under an objective standard of reasonableness for failure to investigate and assert an invalid defense. E.g., Russell v. Jones, 886 F.2d 149 (8th Cir.1989); Mercer v. Armontrout, 864 F.2d 1429 (8th Cir.1988); Cooley v. Nix, 738 F.2d 345 (8th Cir.1984). In addition, investigating and asserting an invalid defense would not have produced a substantial likelihood of a different result. No prejudice ensued.
V.
At the trial, defense counsel asserted Couch’s chosen defense of alibi.24 The prosecution had numerous eyewitnesses to the shooting whose testimony would have nullified the alibi defense. Trial counsel made a tactical decision not to interview these witnesses, who would be available at trial. This decision was a practical choice based on informed and reasoned professional judgment.
The Strickland Court noted that “strategic choices made after less than complete investigation are reasonable to the extent that reasonable professional judgments support the limitations on investigation.” 466 U.S. at 691, 104 S.Ct. at 2066. Counsel had a duty to “make reasonable investigations or to make a reasonable decision that makes particular investigations unnecessary.” Id. The reasonableness of a decision not to investigate is analyzed under all the circumstances, affording great deference to counsel’s judgment. A strong presumption exists that counsel’s conduct fell within the wide range of reasonable professional assistance and under the circumstances might be considered ‘sound trial strategy.’ Id. at 689, 104 S.Ct. at 2065 (quoting Michel v. Louisiana, 350 U.S. 91, 101, 76 S.Ct. 158, 164, 100 L.Ed. 83 (1955)). Since a jury must decide the credibility of eyewitnesses, the alibi defense was still viable at the time it was asserted.
It is clearly not unreasonable for an attorney to pursue a valid defense based on reasonable, professional judgment though it may ultimately prove unsuccessful. Id., 466 U.S. at 699, 104 S.Ct. at 2070. Trial counsel’s conduct in the instant case can be distinguished from the conduct which shocked the conscience of this court in Eldridge v. Atkins, 665 F.2d 228 (8th Cir.1981) (investigation would have produced strong evidence of a “substantial” defense).
VI.
Trial counsel’s conduct did not fall below the objective reasonableness standard of Strickland for determining deficiency of counsel’s performance, or create prejudice serving to taint the fairness of the proceedings. Interviewing prosecution witnesses would not have created a reasonable probability of a different result and would have constituted investigation of the inapplicable statutory mental illness defense, which was properly made the subject of expert testimony.
Refraining from asserting or investigating an invalid defense was reasonable. Pursuing an invalid defense would not have created a reasonable probability of a different result. Therefore, Couch suffered no prejudice. Viewing counsel’s conduct objectively, as mandated by Strickland, this court cannot find that performance was deficient or prejudicial. Couch’s allegations are insufficient under the two-prong Strickland standard to establish ineffective assistance of counsel in violation of the sixth amendment.
We affirm the district court’s dismissal of Couch’s petition for a writ of habeas corpus.
. The Honorable Edward L. Filippine, United States District Judge for the Eastern District of Missouri.
. Couch asserts mental disease or defect based on voluntary intoxication.
. Mo.Rev.Stat. § 559.010 (1939) defined first degree murder as murder "committed by ... willful, deliberate and premeditated killing.” Premeditation and deliberation were necessary elements of this specific intent crime.
. Rule 27.26 was repealed effective January 1, 1988. Post-conviction relief in Missouri is now available pursuant to Missouri Supreme Court Rule 29.15.
. Couch v. State, 664 S.W.2d 233 (Mo.App.1983). At the evidentiary hearing, a St. Vincent’s Hospital psychiatric report, compiled pursuant to a defense motion, precipitated by Couch’s admission of drug and alcohol use, was introduced. The report indicated that Couch was not disoriented, showed no signs of thought disorder, and did not suffer from hallucinations, delusions or any mental disorder. The psychiatrist discovered nothing that would serve to negate responsibility for criminal conduct. After reviewing the report, the Missouri Court of Appeals concluded that Couch failed to show counsel was ineffective in not investigating a mental illness lack of capacity defense due to a "mental disease or defect” caused by intoxication.
. Order, No. 87-493C(2) (E.D.Mo. May 31, 1988). The Report and Recommendation of United States Magistrate Carol E. Jackson, No. 87-493C(2), February 4, 1988, concluded that Couch was not prejudiced by trial counsel’s failure to investigate and present a defense of mental illness when the records supported a diagnosis of alcoholism without psychosis.
. Memorandum and Order, No. 87-4930(2) (E.D.Mo. June 20, 1988).
. Order, No. 88-1925 (8th Cir. Aug. 24, 1988). The purpose of the evidentiary hearing was to take the testimony of Joseph S. Beatty, trial counsel, regarding trial preparation, investigation and consultations with Couch to determine whether a basis existed for Couch’s claim of ineffective assistance of counsel, specifically whether counsel thoroughly investigated the case prior to trial and considered potential defenses. Since counsel’s actions are usually based on information supplied by the defendant, the reasonableness of investigative decisions depends upon such consultations. Strickland v. Washington, 466 U.S. 668, 691, 104 S.Ct. 2052, 2066, 80 L.Ed.2d 674 (1984). The order requested that the magistrate review the record and make findings on these issues. Inquiry was to be made into whether counsel consulted with Couch, interviewed the prosecution’s witnesses and considered defenses to mental culpability mitigating premeditation, an essential element of the crime charged. Order at 2; Evidentiary Hearing Transcript at 6.
. The VA Medical Center report indicated that Couch had been hospitalized previously as a result of acute intoxication. The report stated Couch was well-oriented in all three spheres, was in good contact and denied being mean, hostile or combative, except when under the influence of alcohol. Couch apparently also denied hearing voices or having paranoid delusions but admitted to previous alcoholic binges. The report noted Couch possessed low intelligence and concentrative power. The primary diagnosis was psychoneurotic disorder and anxiety with sociopathic components. The secondary diagnosis was alcoholism. Certificate of Evaluation of Milton R. Couch at 2 (September 17, 1975) (Plaintiff’s Exhibit 2).
. A psychiatric evaluation is ordered when a judge has reasonable cause to believe that the accused lacks mental fitness to stand trial. Under the Missouri statute, a person who lacked capacity due to “mental disease or defect” could not be tried. “Mental disease or defect” within the meaning of the Mental Responsibility Law was defined as a congenital or traumatic mental condition or a disease but not alcoholism without psychosis. Therefore, an intoxicated or drugged condition absent psychosis did not constitute lack of capacity to stand trial.
.The Fulton study stated in pertinent part:
VII. DISCUSSION
This examination of Mr. Couch finds him of average intelligence and in good touch with his surroundings. He shows no obvious signs of mental illness. He is fully aware of the crime with which he is charged although he tends to deny responsibility for it. There is a history apparently of alcoholism. His past diagnosis of manic-depressive illness diagnosed in a private mental hospital is not confirmed in this study. We have also reviewed records from three hospitalizations at a veterans hospital in St. Louis, the last of which occurred just five days after the alleged offense. In brief, those records found him to be without psychosis and without need for further hospitalization. They also note that he *1341had anxiety symptoms, sociopathic traits and also alcoholism. He was considered responsible for his conduct. That report is also descriptive of our current findings.
VIII. FINDINGS
1) That the accused has no mental disease or defect within the meaning of Section 552.-010.
2) That the accused has the capacity to understand the proceedings against him and can assist in his own defense.
3) That the accused did know and appreciate the nature, quality and wrongfulness of his alleged conduct and was capable of conforming his conduct to the requirements of the law.
4) That the accused does not require hospitalization pending further proceedings.
Certificate of Evaluation of Milton R. Couch at 4-5 (September 17, 1975) (Plaintiff’s Exhibit 2).
. The study was not objected to within the statutory period of ten days. Mo.Rev.Stat. § 552.020(6) (1971).
. Strickland v. Washington, 466 U.S. 668, 104 S.Ct. 2052, 80 L.Ed.2d 674 (1984). Both the performance and prejudice elements of an ineffective assistance of counsel claim are mixed questions of fact and law. Id. at 698, 104 S.Ct. at 2070.
. Couch does not argue on appeal that the Missouri statutory scheme was a violation of due process because it failed to provide that voluntary intoxication was a defense to a specific intent crime. Therefore, we do not reach the constitutional issue. A statutory intoxication or drugged condition defense, Mo.Ann.Stat. § 562.076 (1977), was later enacted. The later-enacted statute provided that a person who was in an intoxicated or drugged condition, whether from alcohol, drugs or other substance, was criminally responsible unless such condition (1) negated the existence of the mental states of *1342purpose or knowledge, when such mental states were elements of the offense charged or of an included offense, or (2) was involuntarily produced and deprived [defendant] of the capacity to know or appreciate the nature, quality or wrongfulness of conduct or to conform conduct to the requirements of law. The present statute, as amended in 1983, only requires that the intoxicated condition be involuntarily produced and deprive the defendant of the capacity and ability to conform his conduct.
. 863 F.2d 1377 (8th Cir.1988) (en banc). As in the instant case, trial counsel relied on a Fulton State Hospital psychiatric examination of the defendant which incorporated a previous determination that Laws did not suffer from a "mental disease or defect," knew and appreciated the nature, quality and wrongfulness of his conduct, and was capable of conforming his conduct to the requirements of law.
. Laws v. State, 708 S.W.2d 182 (Mo.App.1986). The Missouri Court of Appeals closely examined the transcript of the Rule 27.26 hearing to conclude as a matter of law that trial counsel made a reasoned, strategic decision not to assert a mental illness defense based on all the circumstances.
. Couch v. State, 664 S.W.2d 233 (Mo.App.1983). Specific factual findings made by a state court should be presumed true in a habeas corpus proceeding alleging ineffective assistance of counsel. See Sumner v. Mata, supra. In addition, the evidentiary hearing held at this court’s direction by the magistrate refutes all claims of ineffective assistance of counsel.
. Strickland, 466 U.S. at 694, 104 S.Ct. at 2068. A "reasonable probability” of a contrary result is a probability sufficient to undermine confidence in the outcome of the case. In assessing prejudice, this court must assume the lower court reasonably, conscientiously and impartially applied the governing standards.
. Strickland, 466 U.S. at 687, 104 S.Ct. at 2064. Reasonable conduct consists of conduct that a competent attorney would undertake under like circumstances.
. Id. at 689, 104 S.Ct. at 2065. An act or omission of counsel is not necessarily unreasonable merely because the defense ultimately proves to be unsuccessful.
. Id. Courts presume counsel’s conduct fell within a wide range of reasonable professional assistance. A court may conclude that under the circumstances, the challenged action would be considered sound trial strategy. Effective assistance is not manifested in one course of conduct.
. Id. Hindsight has a distortive effect. A court should reconstruct the circumstances surrounding the challenged conduct.
. The records which were available to trial counsel for review in preparation for trial included the Veterans Administration medical report completed by a staff psychiatrist, and the certificate of competency filed by the clinical director of Fulton State Hospital, pursuant to the court’s request under § 552.020. Evidentia-ry Hearing Transcript at 24. The medical report stated in pertinent part:
[Couch] was under the influence of alcohol and he doesn't remember that he killed a man.... The patient is well oriented in all three spheres. He is in good contact_ The patient gives a history of having amnesia off and on, and that usually happens when he is under the influence of alcohol.... He admits having a drinking problem.... The patient, in this examiner’s opinion, is not psychotic. The patient must have acute brain syndrome associated with alcohol intoxication and was suffering from amnesia as a result of that.
Plaintiff’s Exhibit 3 (emphasis added).
Counsel contends that he was not aware of the medical report. Evidentiary Hearing Transcript at 45. There was no evidence that Couch made counsel aware of its existence. However, the certificate, which references the medical report and which counsel admits to having reviewed, concluded in pertinent part:
III. MENTAL STATUS
... [N]o obvious signs of being disturbed .... Orientation is intact in three spheres.... Memory is intact for recent and remove events.... [N]o signs of a thought disorder. Hallucinations or delusions are not found.... No inappropriateness was seen in his mood....
VI. DIAGNOSIS
... NO MENTAL DISORDER
VII. DISCUSSION
... [I]n good touch with his surroundings.... [N]o obvious signs of mental illness .... There is a history apparently of alcoholism.... [Wjithout psychosis and without need for further hospitalization.... [H]ad anxiety symptoms, sociopathic traits and also alcoholism_ [Considered re-
sponsible for his conduct....
VIII. FINDINGS
1) [A]ccused has no mental disease or defect within the meaning of section 552.010.
2) ... has the capacity to understand the proceedings against him and can assist in his own defense.
3) ... did know and appreciate the nature, quality and wrongfulness of his alleged conduct and was capable of conforming his conduct to the requirements of the law....
Plaintiff’s Exhibit 2.
. Couch claimed he was visiting his wife in the hospital at the time of the murder.