Law & Order: Special Victims Unit Episode 4.04 Lust

The wife of a retired attorney, a public health doctor, is found murdered and raped in Central Park. Her work involved contacting sexual partners of HIV patients which gives the detectives a long list of suspects. The discovery of a second body in Central Park with the same signature shifts the focus to a serial killer; however, the trail leads to a man who has no knowledge of the crimes but has a distant connection to the doctor and her husband.