David Berkowitz' Dog Collar

Origin
David Richard Berkowitz (1953, incarcerated 1979) is also known as the Son of Sam and the .44 Caliber Killer. Berkowitz told detectives that he was killing on the orders of a demon, manifested in the form of a dog named Harvey who belonged to his neighbor, Sam. In his possessions when arrested was a dog collar with no tags on it, assumed to have been stolen from Harvey.

Effects
When held the person hears voices talk about easy ways to kill people. An Agent who risked hearing what it said reported "I say goodbye and goodnight. Police: Let me haunt you with these words: I'll be back!  To be interpreted as bang, bang, bang."