87th Precinct S01 E11 The Very Hard Sell

A car salesman is found dead in his car, shot with his own gun. The coroner believes it's a clear case of suicide, but the man's wife insists he would not have taken his own life. Lt. Carella searches for the man's last customer. His main clue is two strands of picture wire he finds tied around plumbing in locations where the customer and the victim were supposed to have met.