Who is Joe Morelli from Four to Score and what is their importance?

Joe Morelli is a cop with the Trenton police department. Stephanie and Morelli have known each other since they were small children, having grown up in the same neighborhood. Morelli and Stephanie have had an intimate relationship in the past, but because Morelli has a reputation as a lady's man, Stephanie is reluctant to become further involved with him. However, after her apartment is firebombed by someone Stephanie initially believes is connected to Morelli, she chooses to move in with him until her apartment is fixed.