Law & Order: SVU Season 13 Episode 4 (10/12/11)
Detective Rollins notices striking similarities between two rapes in New York and a case she worked in Georgia. The Atlantic Coast Rapist was responsible for over 15 rapes in 9 years, with victims in Georgia, South Carolina, and Maryland.
A detailed sketch of the suspect leads detectives to family man Gabriel Thomas. Even though he is confronted with an overwhelmingly amount of evidence, including DNA, Thomas repeatedly claims he is innocent.
Detective Amaro begins to believe that Thomas may be telling the truth when he notices some inconsistencies between the rapes and Thomas's alibi, which leads him to discover that the adopted Gabriel has a twin brother. Gabriel's birth mother never told him about his brother, but she did tell his twin, Brian Smith. Smith followed his brother, setting Gabriel up to take the fall for the rapes.
Rollins comes up with a clever trap for Smith, using herself as bait, and the detectives finally arrest the right man. However, he won't confess his crimes until Rollins comes into the interrogation room and coaxes it out of him.