A somewhat glaring issue I haven't seen discussed: when Harrison starts beating up pic related and inflicting that damage, punching him in the face over and over, that would leave severe bruises on his hand.
When the detectives interview Harrison within just a couple days later, his hand would still be bruised up.
So either he has Wolverine-like healing powers, or the detectives never looked at or noticed the condition of his hands despite the forensic evidence of the altercation, which would be retarded