Nicknames: The Ruhr Cannibal, The Ruhr Hunter, The Duisburg Man-Eater
When It Happened: 1955-1976
Number of Victims: 14
Punishment: Life Imprisonment
How He Did It: Kroll confessed to 14 murders, saying that he often sliced off portions of his victims' flesh so that he could later cook and eat them in order to save money on groceries. He was caught in 1976 in the process of doing so to his most recent victim; when police entered his home, a hand was cooking in a pot of boiling water, and the victims' internal organs had clogged the waste-pipe.