Law & Order: Special Victims Unit: Season 6, Episode 6

Conscience

The son of psychiatrist Dr. Brett Morton (Kyle McLachlan) disappears from a birthday party, and is found dead by the police. Despite viewing his child's body in the morgue, Morton remains perfectly calm and asks carefully laid questions about his son's death, which fills the detectives with unease. When it becomes clear that the little boy who helped the investigate is actually the killer, the police question children who knew the killer. Testimonies bring to light that the boy is a sociopath with violent tendencies, who is treated leniently by the court. As a result, Dr. Morton loses his composure in court and fatally shoots the boy. As a claim of defense during his subsequent trial, Morton claims he was not aware of what he was doing, and his despair overrode his senses. He rationalizes that the killing was just, because the unrepentant boy would have just gone on to kill again, but he, Dr. Morton, wouldn't.