Investigators discovered that Rick Van Thiel had been conducting unlicensed medical procedures — including abortions — in his trailer clinic, treating everything from cancer to STIs.

Carol Giles and Tim Collier tortured her friend, Nancy Billiter, after they became convinced that she had overheard them discussing the murder of Carol’s late husband. 

Jenna Oakley and her boyfriend, Kenneth Nigh, were captured sleeping in the parking lot of a New Mexico motel just days after her stepmother’s brutal murder.

While Thomas Gilbert, Jr. Was tall, fit, and good-looking, friends described him as awkward and prone to violent outbursts.

Dr. Anthony Pignataro became a minor celebrity for offering bargain cosmetic surgeries, but his basement room of horrors soon landed him in court.

Maria Hernandez wired her brother $800 to murder her husband, Enrique Hernandez, after he found out she was having an affair.

After Vietnam War veteran Bob McClancy was found dead of an apparent suicide in 2006, a years-long investigation uncovered a tale of lies, betrayal, and greed.

When Brooklyn Reynolds’ mother and stepfather forbade her from seeing her older boyfriend, the two hatched a deadly plan to be together.

"Mark of a Killer" is looking back on the mementos and calling cards of some of the most horrific serial killers in U.S. history.

Bernita “Billie” Cunningham was found dead in her home in 2006 after apparently suffering a fatal fall. A closer look at the scene, however, suggested the possibility of foul play, and a years-long hunt for the truth began.