Obsession - S2.E9

Chase and August investigate the murder of a young fashion model who appears to be the latest victim in a string of recent model killings. Judith Sands, the L.A.P.D. psychologist, with connections from a previous (though short-lived) modeling career, convinces the detectives to let he go undercover to help find the killer. Chase and August are thrown onto the trail of a mysterious freelance photographer who has been hanging around the shows, and they are led on a wild chase before they can bring him in for questioning. But the suspect's DNA doesn't match that of the murderer's, and Chase and August must let him go and continue the search for the killer, who has decided on making Judith his next victim.