Watch World's Most Notorious Killers

Tourists in Southeast Asia are mysteriously killed, and Charles Sobhraj confesses to the horrific murders. Convicted murderer Sobhraj, now a free man, speaks out in an U.S. exclusive interview to reveal a shocking new story.

Lynette Dawson, a loving wife and mother, disappears from her Australian home in 1982; days later, her husband, Christopher Dawson, moves their teenage babysitter into their home. It will be 40 years before the case is finally solved.

Six Belgian girls mysteriously go missing at the hands of "The Monster." But soon, people begin to suspect that Belgium's infamous serial killer may be working for a powerful international pedophile ring.

A perplexing series of deaths in Vienna, Austria are linked to murders in Los Angeles, California. Austrian celebrity Jack Unterweger is unmasked as the world's first transatlantic serial killer, whose been reporting on his own murders and hiding in plain sight all along.

The case of a missing girl leads to a gruesome discovery: a graveyard of bones beneath the house of Fred and Rose West in Gloucester, England and several twisted family secrets.