damage; and child abuse. We agree. Deficient Performance Counsel has a duty to conduct a reasonable investigation so that he can make an informed decision about how best to represent his client. Strickland, 466 U.S. at 691, 104 S.Ct. 2052. Thus, counsel may render ineffective assistance “where he neither conducted a reasonable investigation nor made a showing of strategic reasons for failing to do so.” Sanders v. Ratelle, 21 F.3d 1446, 1456 (9th Cir.1994). We have held that a failure to investigate and present, at the penalty phase of a capital trial, evidence of organic brain damage or other mental impairments, drug abuse, and a dysfunctional family or social environment may constitute ineffective assistance of counsel. See, e.g., Caro v. Calderon, 165 F.3d 1223, 1226 (9th Cir.1999) (<HOLDING>); Wallace v. Stewart, 184 F.3d 1112, 1115 (9th
holding trial counsel ineffective for failing to investigate and present evidence of the appellants good conduct in prison holding that counsels performance was deficient for failing to investigate readily available evidence of mental impairment holding that counsel was ineffective for failing to investigate defendants mental impairments caused by childhood exposure to toxic chemicals holding that where trial counsel was not ineffective appellate counsel was not ineffective for failing to raise claim of ineffectiveness of trial counsel holding counsel ineffective for failing to investigate and present mitigating evidence