Fritz Haarmann, "The Hanover Vampire", had a butcher shop in Hanover, back in the early 1920's. He would often go to the train station where he met young boys, all under 20. He would would offer them shelter and work. Upon returning to his home he would feed them and then kill them. It was brought out at his trial that he was in a trance while the actual killing was done.
Funny thing though he actually killed them by biting them in the throats. This gentleman was not one to waste as he sold human flesh sausage, under a different name of course, in his shop and apparently it was a big hit with his customers.
Bon Apetit
here is some more info on that note.
Fritz was born on October 24, 1879. He hated his father who was a locomotive stoker. Fritz didn't do well in school so he joined the service and was a good soldier. When he returned to Hanover he was accused of molesting children. He was placed in a mental institution but he broke out and went to Switzerland. Fritz eventually came back to Hanover where he fought with his father so he enlisted in the 10th Jager Batallion at Colmar in Alsace. He was released with a medical discharge. Fritz again went home to his father but the fighting turned physical. With no legal cause to commit Fritz to an asylum he lived on the streets. He survived by stealing and other crimes for which he was sent to jail. He was released from jail in 1918. Fritz butchered and sold meat. He then became a spy and police informer where he got the nickname Detective Haarmann. Fritz would stroll before dawn through the railway station at Hanover and awaken a sleeping boy demanding to see his ticket. When the boy didn't show a ticket and told his sad story Fritz would offer the boy a place to stay for the night. Fritz's first victim was a runaway named Friedel Rothe who was seventeen. The police followed his trial and found him in a sexual act with another boy which violated Section 175 of the German Code which was punishable by nine months in prison. Four years later when he was awaiting trial for twenty-four killings he confessed. Fritz bit into his victim's throat and tasted the flowing blood. All of Fritz's victims were between the ages of twelve and eighteen. He actually sold the flesh of his victims for human consumption. The Hanover Vampire was found guilty and sentenced to death. He said, "I want to be executed in the market place. On my tombstone must be put the inscription: Here lies Mass-Murder Haarmann. And on my birthday, Hans Grans must come and lay a wreath on it." He was beheaded on April 5, 1925.