The body of a woman who was beaten and shot is found to be the same woman who stole the identity of Chief Carver's sister 15 years ago. The bullet from the victim's body is linked to a gun registered to Chief Carver which adds to makes initial suspensions that Carver was somehow involved in his sister's murder. Carver claims he lost the gun years ago but never bothered to report it; Mac isn't buying it and knows he is hiding something. The team finds the victim's true identity, Marcella Gomez, and discovers she was an illegal immigrant who married an abusive man for a green card. She stole Roni's identity to stay in the country and ran from her abusive husband. The team tracks the husband down and he admits to murdering Marcella. He claims that he used the gun from her purse to shoot Marcella but has no idea who Roni Parker is. Hitting a dead-end, Mac decides to re-examine the forensic evidence from Roni's body and finds the DNA from the chewing gum found with her body matches to her son. Roni was an abusive mother and her son Jay had enough and planned her murder. Carver knew what happened but also knew that Roni's children suffered horrible abuse and he never stepped in to help them. He took the children in and raised them like his own and buried the secret to protect Roni's son Jay. Carver gave Marcella, Roni's identity to help her run from her abuse situation. Mac is relieved his colleague is innocent of the murder but knows Carver will be disgraced and fired for doing what he thought was right for his nephew.