The Perfect Crime? Or Double Trouble? I’m pretty sure this was on an episode of Law & Order. From the Times:

At first, the murder case against Orlando Nembhard seemed solid, as witness after witness came forward to say they saw someone that looked just like him brandish a pistol in February outside a crowded nightclub and fire on a young clubgoer, who later died.

But the case has turned shaky because someone who bears a striking resemblance to Mr. Nembhard — his identical twin brother, Brandon — was also at the scene in the early in the morning of Feb. 12.

Now the question facing the police and prosecutors is whether the right twin — Orlando, who goes by the nickname Slick, or Brandon, better known as Blizzy — was charged in the killing of Sir Xavier Brooks, 19, who had his hands up and was backing away from the gunman when he was shot in the abdomen.

With no forensic evidence pointing to the gunman’s identity, the police said, it comes down to the witnesses.

Now Jack McCoy would try each of the defendants simultaneously, and go for a double-guilty verdict.

“This is a case of mistaken identity,” Mr. Lamm said. “The very keys that unlock Orlando’s jail cell could be the ones that lock up his brother.”

Those keys could also allow both brothers to be free, legal experts say, if jurors have reasonable doubt as to which twin was responsible.