The head of Diogo Alves (1810-1841), one of the most famous portuguese serial-killers and one of the last criminals to be sentenced to death in Portugal. He would kill his victims by attacking them at the top of the Águas Livres Aqueduct, in Lisbon, and throwing them off of it - a 65m (213 feet) fall to their death.
Sources from 1837 say he killed more than 70 people.
Initially seen as a rather strange suicide spree, Alves method was given away when he killed 4 people from the same family.
He was hung and his head was kept in formol so his condition (his “evil nature") could be studied.