When a restaurateur is killed, police trace the murder to a man with a taste for human flesh.

Examining rumors surrounding the NXIVM cult and its leader Keith Raniere.

On the search for Shannan Gilbert, the bodies of four women, all in their 20s and presumed to be sex workers, were found over three days. They were all fully intact skeletons discovered in burlap.

Since 2010, 17 bodies have been discovered in and around New York's Gilgo Beach. The bodies found were of female escorts who solicited their services on Craigslist. Could a group of people be responsible?

Enter Oak Beach: a desolate community considered a party town in the 1970s.

Since 2010, 17 bodies have been discovered in and around New York's Gilgo Beach. Authorities believe this could be the work of the Long Island Serial Killer.

On the night of her disappearance, Shannan Gilbert frantically called 911 saying, "They’re Trying to Kill Me!"

The Long Island Serial Killer is believed to have murdered Shannan Gilbert- but the Gilbert family has suffered another shocking tragedy. Shannan’s mother Mari was murdered on July 23, 2016, two months after her interview with Investigation Discovery’s People Magazine Investigates.

In 2010, a vivacious young escort, Shannan Gilbert, visits a client on the south shore of Long Island and vanishes under mysterious circumstances. Her disappearance leads police to the bodies of other victims buried along the shore. This discovery unleashes a wave of secrets, suspects, recriminations and conspiracy theories in the hunt for a serial killer who targets prostitutes.

In 2011, Kansas City: Electrician Jeremy Irwin returns home after a late-night shift and his 10-month-old daughter Lisa is missing. He wakes up his fiancée Debbie Bradley and their two young sons and the family frantically searches for Lisa. She is nowhere to be found. Police initially focus their investigation on neighbors and drifters, but in a stunning turnaround, accuse the family of being responsible. As the case gains national attention and the two sides battle it out in the media, reputations are ruined, relationships are broken and the fate of a small child is left hanging in the balance.

Sarasota, Florida: 1991. Outgoing Jackie Galloway is found strangled and bound with ritualistic knots. Police investigate a number of likely suspects in her inner circle but are shocked when a chance encounter with a prowler leads them to discover the murderer is a budding serial killer.

BTK taunts authorities through local media, including Wichita's KAKE-TV.

BTK's daughter tells of learning that her father was a notorious killer.

A psychologist relays BTK's own story about how he became a killer.

Detectives share some of BTK's own meticulous documentation of his crimes.

A victim's son receives disturbing letters from a mysterious author.