German animal rights activists have urged prions authorities holding an alleged cannibal killer to switch his diet and have gifted him a booklet for vegan starters.
Activists with Peta said Detlev Guenzel, a 55-year-old police officer who admitted killing and chopping up a man he met on the internet, might benefit from giving up meat.
"Indifference towards animals' suffering often leads to cruelty towards people," said Peta biologist Tanja Breining.
"A meatless diet promotes compassion for all living beings and therefore non-violence."
Peta cited some recent university studies saying that a vitamin-rich diet may reduce prisoners' aggressive behaviour.
"No living creature belongs to the kitchen," Peta said.
Guenzel was arrested in November in the eastern city of Dresden over the killing of Wojciech Stempniewicz, 59.
Guenzel, a handwriting and document analysis specialist, confessed to police fatally stabbing and dismembering Stempniewicz, who he had met on an internet website for people obsessed with cannibalism called Zambian Meat.
Police said Stempniewicz had long fantasised about being killed and eaten.
Guenzel admitted burying Stempniewicz's body parts the parts in various spots around his property near the town of Hartmannsdorf-Reichenau, south of Dresden, hours after the two met in person for the first time.
Guenzel denies cannibalism, although some body parts and organs have not yet been retrieved by police.
The case mirrored that of Armin Meiwes, a former German military official who was arrested in 2002 for killing and eating a man he met online.
Meiwes, who is serving a life sentence over the murder, was also gifted a vegetarian cookbook by Peta in 2003.