Defense experts argued that Dahmer was insane due to his necrophilic drive – his compulsion to have sexual encounters with corpses. Defense expert Dr. Fred Berlin testified that Dahmer was unable to conform his conduct at the time that he committed the crimes because he was suffering from paraphilia or, more specifically, necrophilia. Dr. Judith Becker, a professor of psychiatry and psychology, was the second expert witness for the defense; Becker also diagnosed Dahmer with necrophilia. The final defense expert to testify, forensic psychiatrist Dr. Carl Wahlstrom, diagnosed Dahmer with necrophilia, borderline personality disorder, schizotypal personality disorder, alcohol dependence, and a psychotic disorder.