Not sure if "often", but he admitted to having drunk the blood of a victim at least once.
Also, weird music for lovers of serial-killer-inspired death-metal: youtube.com/watch?v=2CilDq5ISW4
Antoine Lavoisier, beheaded in the French Revolution. He was an insanely brilliant scientist and this "experiment" was his way of coping with his death by guillotine. He got sixteen blinks in, iirc, before his head died. His death was a terrible loss for humanity..
A Dr Beaurieux went further: a few seconds after the eyes of the freshly beheaded man closed, he called his name, and the severed head opened his eyes again and looked directly to him.
Also, weird music for lovers of serial-killer-inspired death-metal: youtube.com/watch?v=2CilDq5ISW4