Threilkis is a crime lord in Sudden Impact. He is a big time mobster and a very old man. Harry Callahan arrives at the wedding of Threilkis' grandaughter to tell him about a murdered hooker names Linda Doker. Harry tells him that the hooker wrote down a lot of information about her client. Obvioulsy Threilkis was the one who had her killed. The old man had gotten so upset about the fact he didn't get away with the crime and that their was evidence he had a heart attack. His death causes his goons to repeadetly try to assasinate Harry. Harry encounters one of the goons in San Paulo.