Preview Mark of a Killer Returns on April 9th at 9/8c Oxygen Insider Exclusive! Create a free profile to get unlimited access to exclusive videos, breaking news, sweepstakes, and more! Sign Up for Free to View Mark of a Killer Returns on April 9th at 9/8c Oxygen's original series "Mark of a Killer" returns Thursday, April 9th at 9/8c. Watch the Full Episode
