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.

Detectives reveal the weather was vital in Trent Mallory’s case.

What happened to the Memphis businessman?

Dr. Jim Sowa is killed by his patient, Joey O'Boyle, who had a history of violence and mental health struggles.

Investigators find a partially packed suitcase in Joey O'Boyle's home.

Preview: It is quickly discovered that Carmela Knight died from blunt-force trauma before being badly burned in a house fire.

After Uloma Curry-Walker's frantic 911 call, firefighters on the scene recognize Lt. William Walker, a fellow firefighter.

Friends and family tearfully recall the night that led to Carmela Knight's death.

Season 3 Preview: "Trader Trent's" following on Facebook Marketplace opened up a range of possibilities for detectives.

Learn more about Patricia McDermott's fatal shooting in Philadelphia, and what police later found out about her killer Juan ...