You Be the Judge!! Murder or Suicide

August 1994 Unsolved case on the BlueRidge Parkway. Can you figure out if this is a murder or suicide?? No shot or wadding found! In Kevin's head or in the car. Changed entry wound from 1/8th in. to 1 1/8 in.... when questioned! Firing pin and casing didn't match up!? Shot beneath the chin,found sitting on console of car. No blood on inside roof of car in pics and only small piece of brain matter on back seat. Gun extremely rusty and bloody. Told to leave it alone by Investigator!!! WHY?????