At first I thought it was the Ex-Thompson Needles guy (Michael Biehn) but in the final scene before Mike is found dead when he pulls out of the drive way of Price's home - a car starts to follow him. No explanation of who that was.
shareI think that was thrown in there to cast doubt on the official police finding that Mike's death was by a self-inflicted drug overdose. Since no official reports confirm this part of the movie, I chalk it up to artistic license at best, speculation at worst.
There are no problems that cannot be solved with a can of brake clean and a lighter