Dateline: Unforgettable

Michigan mom Renee Pagel was found stabbed more than 50 times in her home on Aug. 5, 2006, just days after she donated one of her kidney's to the father of one of her nursing students. 

They seemed to have the perfect marriage, until one of them ended up dead.

Thad Harper's brutal death would unravel dark secrets and a stunning betrayal.

The wounds California nurse Sherri Rasmussen suffered in her final moments of life were "extensive and disturbing," but it would take more than two decades to reveal the surprising killer. 

Solving this decades-old cold case took one woman's courageous choice to come forward, advances in DNA technology, and some chilling words from the killer himself. 

For months, Chris Smith's family believed he was taking a once-in-a-lifetime trip around the world, until discovering the heartbreaking truth.

Bob and Jane Bashara had a seemingly idyllic life in Grosse Pointe Park, Michigan, until Jane was found dead and her husband's secret life and dark fantasies were exposed. 

Nick Hacheney was viewed as a charismatic and devout man of God, but parishioners would say he used his faith to manipulate others in dangerous ways.

Joseph Sonnier, a man with seemingly no enemies, was gunned down in his Lubbock, Texas home in 2012.

Casino magnate Ted Binion was found dead in his home in 1998 surrounded by heroin and drug paraphernalia, but investigators began to suspect that his death may have had more sinister origins.