Hello. I can’t remember the name of this movie I saw a few years ago. It’s about this man who is a criminal, on top of the food chain, but on the outside he looks like a great guy, nobody knows that he’s a criminal. He’s girlfriend is a detective, but she doesn’t know, that he’s the one she’s actually looking for. I think at the end she find out.
Dexter (Season 1)
https://www.imdb.com/title/tt0773262/
Dexter’s sister Debra (a Homicide detective) unknowingly starts dating Rudy (The Ice Truck Killer)