IMO.......craig walked in on this, kelly flipped over several things, the imbezzeling, the affair the meth etc........she used the stun gun to kill her.
Titus spent time in prison and he obviously had a soft spot for Melissa, not to mention a guy his size would not need a stun gun to kill her, it would take all of 10 seconds to choke her out. He NEVER wanted to go back to jail.
Titus, then trying to help his wife, tried to dispose of the body, but the plan failed.
Titus is guilty of Arson.....that's about it if you ask me, it's also why his attorney keeps claiming he is 100% innocent.