World's Most Evil Killers - Season 4

A chilling profile of the serial killer Todd Christopher Kohlhepp, who claimed the lives of at least seven innocent people between 2003 and 2016.

A profile of the serial killer who found himself at the center of New York's biggest manhunt after a vicious shooting spree that left six dead.

A profile of The Truck Stop Killer, who targeted hitchhikers and truck stop sex workers in a horrific string of crimes spanning 15 years.

A profile of the murderer known to some as the Riverside Prostitute Killer, who sits on death row after being convicted for the slaying of 12 women.

A profile of the Rhode Island family man and Sunday school teacher, who also turned out to be a cold-blooded triple murderer.

An investigation into the murderous mother-and-son duo, who killed their elderly landlady in a greed-fuelled ploy.

A profile of the serial killer who took the lives of six victims in one month, known to some as The Vampire Killer due to his penchant for cannibalism.

Known as The Railroad Killer to some, the serial killer is thought to have taken the lives of more than 23 victims before his execution in 2006.

A look at the lives and crimes of a duo of cousins who, together, took the lives of 10 girls and women aged between 12 and 28.

A look at the life of the American serial killer, who was convicted of three murders but confessed to many more.