Hunter (1984)

S1E17 The Last Kill

Hunter and McCall pursue a contract killer who consistently leaves a napkin marked with a purple circle at every murder scene. Hunter suspects that the murderer is connected to his ex-girlfriend, a once-famous model. McCall thinks Hunter's fixation on his ex's husband stems from jealousy. Meanwhile, Hunter's former flame is convinced her spouse is being unfaithful, completely unaware of the dark truth behind his actions.