Bobby D

Detective Robert Dershowitz (Todd Williams) (or Bobby D, as he prefers to be called), is a homicide detective who's frequently assigned to cases involving Mary's witnesses.

He's pretty sure he's got Mary's number—that she's a U.S. Marshal working for WITSEC—and doesn't hide his disgust for the branch of law enforcement that puts known criminals back on the street.  No matter how many times he asks, Mary always refuses to confirm or deny her role and the true identities of the homicide victims, yet sometimes he lets her play him anyway, fully aware of her intentions.

Now Mary may owe him a favor. If it weren't for Bobby D's tenacity as a detective, Mary would never gotten out of the kidnapping ordeal alive.