He was a serial killer who raped and then ate his victims.
Google Jeffrey Dahmer and click on images.
Besides his confession and eyewitnesses the body parts in his apartment were a dead giveaway. (No pun intended)
Jeffrey Dahmer was not really worried about his fingerprints. The way he carried out his crimes, all evidence was kept inside his apartment which means he had almost total control over anything...
Today's documents inticated no evidence to that.