Mark Suspects That His Wife Has Been Cheating on Him

Mark suspects that his wife has been cheating on him. In order to confirm his suspicions, he leaves work early in hopes of catching his wife "in the act." As he suspected, Mark's wife was in bed with his best friend. Mark threw down his briefcase, broke some dishes in the living room, and left the house. The next morning, Mark drove to his best friend's apartment. He took a gun out of his glove compartment, walked up to the door, and when his best friend answered, Mark shot him three times. Mark then called the police and stated that he had just murdered his best friend. He did not attempt to flee, but instead waited for the police to arrive. What facts support a conviction for voluntary manslaughter? Could Mark plead voluntary manslaughter based on the claim that his best friend insulted him when he answered the door? Why or why not? What if Mark would have shot his best friend when Mark walked in on his wife and best friend?