I was married to the "nicest guy in the world" by the accounts of his friends and family. After a few fast drinks, he turned into an abusive maniac. His rage was always just below the surface and alcohol brought it to light.
Based on the short period of time that elapsed between parking the car and shooting, I'd say MD runs on a very short fuse with a few drinks in him.
I wonder if MD perhaps had more than she's reporting. She saw 3 or 4. But, who knows how many he had when she wasn't observing him.
I believe that he ran because he knew his blood alcohol would test over the legal limit.
Enough of the talk about pizza! Did you and Michael have any concerns that you were responsible for the death of a young man? You were complicit in a killing for g*ds sake!