When trial counsel in a capital case presents anecdotal evidence of prenatal exposure to alcohol and evidence of learning disability but not expert testimony regarding Fetal Alcohol Spectrum Disorder (FASD) and its resulting organic brain damage, is the failure to investigate and present evidence of organic brain damage prejudicial under Strickland v. Washington, 466 U.S. 668 (1984)?

When trial counsel in a capital case presents anecdotal evidence of prenatal exposure to alcohol and evidence of learning disability but not expert testimony regarding Fetal Alcohol Spectrum Disorder (FASD) and its resulting organic brain damage, is the failure to investigate and present evidence of organic brain damage prejudicial under Strickland v. Washington, 466 U.S. 668 (1984)?