Chuck's Death Was Ruled as a Suicide

Don Devereaux's death was ruled as a suicide. He had been walking around wearing a bulletproof vest for weeks and then he's found shot in the head. The gun that they found at the scene, yes, it was Chuck's, but had no fucking fingerprints on her. And also when they tested Chuck's body, they found gunshot residue on his left hand. Why would he shoot himself with his non-dominant hand? That doesn't make sense either. Then we've got the weird tooth wrapped up in the handkerchief on the back seats of the car. Also, why did he have instructions telling him how to get to where he was going to kill himself?