Comey is clinically mentally ill. I’m not an expert but I would start with “delusions of grandeur”, narcissism, sociopathic, etc.
Hes very careful to ask for clarification on a question so that he does not answer in a way that he incriminates himself. He does not use pronouns which are vague and can be used against you. Unfortunately Trump uses pronouns all the time and then gets called on for something that he never meant to say.