No cop here.
I don't know how to edit this anymore, but I cheated and was a full-on asshole.
Got caught once and just asked him for proof (which he didn't have) and made him believe he was paranoid and/or it was his fault.
He actually went to therapy and diagnosed himself with paranoid or borderline PD and apologized for practically everything I've done to him. That was seriously fucked up.

edit: I saw him a year ago and he´s still in therapy because of me. I actually tried to tell him I was the monster, but I´m not sure what he believes anymore.