The 2013 slaying of a beloved businessman in Washington state helped federal officials not just uncover another man’s disappearance some 800 miles away, but led them to a group of violent men ...

Find out why Joseph O’Boyle brutally killed his doctor, beloved chiropractor James Sowa, in his Bensalem, Pennsylvania, home, and how detectives found him.

Learn more about the investigation into Michigan man Trent Mallory's 2014 murder, as told in Oxygen's Killer Relationship.