Karl Denke was born in Ostrau in Prussian Silesia, now Ziebice in Poland, on August 12, 1870, to a prosperous farming family. He inherited land, failed at farming, sold up, and by the 1920s owned a house in the village where he lived on the ground floor and let rooms.
He played the organ at the Lutheran church, carried the cross at funerals, and was known to everyone as Papa Denke because he gave money and food to beggars.
Germany after the war and through the hyperinflation of 1923 was full of people on the road: demobilised soldiers, the unemployed, journeymen, homeless women. They came through Ziebice constantly and nobody counted them.
That is the condition the case depends on. Denke took them in, killed them with an axe or a pick, and butchered the bodies in his rooms. He pickled the meat in brine, ate it, and sold it at the market as pork. He is remembered as the Cannibal of Ziebice, after the town's present name.
On December 21, 1924 a coachman living upstairs heard shouting and found a young man named Vincenz Olivier on the stairs with a head wound, saying Denke had attacked him with a pick. Denke was arrested and hanged himself in the police cell that night.
The search of the house then found two tubs of meat in brine, pots of fat, bones, braces and belts made from human skin, and a ledger in which Denke had recorded the names, dates and weights of more than thirty people since 1921.
He kept a ledger. He was not hiding what he did from himself, and he was not caught by anyone noticing that people who went into his house did not come out. He was caught because one of them got up and made it to the stairs.
The German authorities of the day suppressed the details, and the case is far less known than Haarmann's, which broke in the same period. The final figure is usually given as at least thirty and possibly more than forty.
Sources disagree on his date of birth. Most accounts give August 12, 1870, the date used here; the current Wikipedia entry instead gives February 11, 1860 and a different birthplace. Accounts also differ on whether he hanged himself with a handkerchief or with his braces. That he died in the cell the night after his arrest is not disputed.