In 2012, Toni Henthorn is hiking in the Rocky Mountains with her husband, Harold, to celebrate their twelfth wedding anniversary. Tragedy strikes when she falls from a 160-foot cliff. Is it a terrible accident or something more sinister?

The tragic case of aspiring model Rhonda Casto, who falls 150 feet to her death from a narrow mountain trail in Oregon's Columbia River Gorge while on a hike with her boyfriend, Stephen Nichols.

The horrific case of mother-of-three Nada Huranieh, who is found dead on the patio beneath an open second-floor window at home by her 14-year-old daughter.

The gruesome case of Leslie Neulander, who dies at home in the arms of her husband, Dr. Robert Neulander, following a 9-1-1 call by their daughter, Jenna.

The chilling case of Cody Johnson, who is pushed to his death almost 200 feet into a ravine at Glacier National Park by his wife of only 8 days, Jordan Graham.

The shocking case of Carol Hickok, who is found dead at the foot of a staircase outside her home by her 11-year-old stepson after she fails to wake him for school.

The mysterious case of millionaire Steven Clayton, who is found dead at the foot of a staircase in the luxury mansion he shares with his wife, Lana.

The horrific case of 30-year-old Natalie Harker, who is found dead in a tent following a 9-9-9 call from her ex-boyfriend, Andrew Pearson.

The tragic case of John Chipp, who is thrown 85 feet to his death after a night out celebrating his 18th birthday.

The horrifying case of Mary Gough, who is found dead at the foot of a staircase at the home she shares with her husband, Colin Whelan.