Where or When - S3.E11

A serial killer who kills with his bare hands leaves the bodies of his male victims at the Brown Derby, the Trocadero, and other Hollywood landmarks. Sam profiles the killer as someone trying to rectify some trauma he experienced in his past. The team follows a trail of clues that eventually leads them to a rather ordinary cab driver who does not seem to have the strength necessary to commit the crimes. A search of the man's apartment yields evidence however, that matches Sam's profile to the letter. The cab driver easily passes a lie detector test. The conflicting findings lead to the release of the man. It is later learned that all the victims were abusers of women. Sam soon realizes the man suffers from multiple personality disorder. His alter ego is a gangster-like tough guy who is bent on avenging the murder of the cab driver's abused mother forty years earlier. B-Story- Sam learns her scientist father participated in experiments that had deadly consequences.