Law & Order: Season 11, Episode 21

11 - 21: Brother's Keeper

Briscoe and Green discover that a murdered businessman may have been the target of a well-known criminal, but the investigation stumbles when the FBI acts as the suspect's alibi. The case gets even more complicated when the detectives find out the suspect has a twin brother, that both brothers had a motive for killing the victim and they can't be sure who was actually the murderer.