"I am not familiar with prison experiments." Which is not to say that he's never spent any time in jail, but. Any experiments he might have willingly or unwillingly participated in occurred outside those bars.

"But you are living with two men who already have blood on their hands," Doc points out. They may not be serial killers but they are very good with their guns, and they live in very grey areas. Doc was arguably of very sound mind every time he had pulled the trigger. He can't imagine Raylan wasn't, either.

"I do not wish for that to happen, or for anyone's death. But I had many chances to retire to a farm, raise chickens. I did not take them." Some asshole does not need to enumerate his list of sins and turn him away from the pearly gates for him to know his debts.

"If it comes to that, I will do my best to protect you. And I do not want my choices to weigh on your mind."