During the 1950s and '60s, the CIA used brainwashing, hypnosis, and torture on thousands of subjects brutalized by the infamous Project MK-Ultra experiments.

Alexander Pichushkin was found guilty of murdering at least 48 people in a Moscow park — and during his trial in 2007, he demanded that the court recognize that he had actually killed many more.

Filled with calcium-coated cliffs and mineral pools, Pamukkale is a UNESCO Heritage Site in southwestern Turkey that attracts hundreds of thousands of visitors a year.

The candiru is a tiny parasitic fish that lives in South America — and supposedly has a penchant for swimming into the human penis.

The self-described prophet of the Branch Davidians cult, David Koresh led his followers into the Waco siege that left 76 of them dead in April 1993.

Known as the "Rotenburg Cannibal," Armin Meiwes killed and ate a willing victim named Bernd Brandes in 2001 before storing the leftovers for 20 months in a hidden freezer.

Gunned down in Medellín on December 2, 1993, "The King of Cocaine" allegedly was shot by Colombian police. But who really killed Pablo Escobar?

Bobby Dunbar vanished in 1912. His reappearance would lead to a custody battle, a possibly wrongly convicted man, and an incredible DNA test 90 years later.

After her husband died, firearms heiress Sarah Winchester built a "mystery house" — allegedly to escape the ghosts of people killed by Winchester rifles.

The Sentinelese have remained almost completely uncontacted on North Sentinel Island for nearly 60,000 years — and anyone who has tried to contact them has been met with violence.

Over the course of 40 years, Sarah Winchester had the so-called Winchester Mansion built in San Jose to her bizarre specifications — in order to appease the ghosts she thought were haunting her.