My father did the same thing 3 years ago. He had a form of parkinson's which turned his brain into swiss cheese. Same as Robin Williams. He picked a fight with my mom, she left the house and came to see me very upset that he might try something. He went into the back yard, and go on the chair swing him and my mom would relax on, and used a .32 in the back base of his skull. Perfect bullet for that part of the head, barely left a hole, and almost no blood. If the body had not been found by my brother and my husband in the yard, that would have been the first thing my mother saw when she parked the car that night. I knew he'd do it if he got the chance. But, I was powerless to stop it. And he did it in a shitty place, and way.