Law & Order: Criminal Intent S06E04 - Maltese Cross

When a New York fire fighter is found stabbed to death, the ensuing investigation and questioning launches Detectives Logan and Wheeler into a brawl with the fire department. Through flashbacks, the Detectives learn that the victim, fire fighter Ian Duffy, helped break up a hate crime but was subsequently found stabbed to death right afterwards. As they investigate Ian's past through his wife Claudia and colleague Brendan Keele, the Detectives learn that Ian's sexuality may have cost him his life.