He’s being charged for manslaughter, which is when death is caused indirectly by the reckless actions of someone. I doubt that Bubaris had the intent to kill Perez, and the autopsy shows that the blow to his gut would ordinarily have not been enough to kill him. However, his alcohol-weakened immune system made even that blow(s) strong enough to kill him. He was also complaining about his stomach when he made the 911 call hours before.
Thanks. Those seem to be some good the point comments. Very good.