Even though defense counsels investigation into a possible mental defense was “minimal” (as concluded by the referee who conducted the evidentiary hearing pursuant to an OSC), the Court did not need to decide whether competent counsel would have investigated further because the failure to do so resulted in no prejudice. Petitioner produced no credible evidence of insanity or absence of intent to kill, which would have been the only possible mental defenses. The trial court heard evidence of drug usage and argument that petitioner had no intent to kill. Therefore there was no reasonable probability the outcome would have been different had counsel investigated a possible mental defense. Further, counsel was not ineffective for advising appellant to waive a jury trial and there was evidence that he had a tactical reason to so advise.