Kroll was a German serial killer and cannibal. He was known as the Ruhr Cannibal (Ruhrkannibale), and the Duisburg Man-Eater (Duisburger Menschenfresser). He was convicted of eight murders but confessed to a total of 13.
On July 3, 1976, Kroll was arrested for kidnapping and killing a four-year-old girl named Marion Ketter. As police went from home to home, a neighbor approached a policeman and told him that the waste-pipe in his apartment building had blocked up, and when he had asked his neighbor, Kroll, whether he knew what had been blocking the pipe, Kroll had simply replied; “Guts”. Upon this report, the police went up to Kroll’s apartment and found the body of the Ketter girl cut up: some parts were in the fridge, a hand was cooking in a pan of boiling water and the intestines were found stuck in the waste-pipe.
Kroll said that he often sliced portions of flesh from his victims to cook and eat them, claiming that he did this to save on his grocery bills. In custody, he believed that he was going to get a simple operation to cure him of his homicidal urges and would then be released from prison. Instead he was charged with eight murders and one attempted murder. In April 1982, after a 151-day trial, he was convicted on all counts and was given nine life sentences.
He died of a heart attack in 1991 in the prison of Rheinbach, near Bonn.