Casey replaced Alexandra Cabot in the episode "Serendipity" after Cabot joined the Witness Protection Program. Elizabeth Donnelly later states that she has a 71% conviction rate.At first, she did not get along with the SVU detectives, particularly Elliot Stabler and Olivia Benson, who saw her as arrogant and distant.Eventually, however, she learned how to be more of a team player, and became close to the SVU squad.Her first case dealt with a child rapist and Casey ended up saving one of the victims herself, figuring out that the rapist, Peter Nestler, was a fisherman and later where he stashed the girl.Little does she know she'll be seeing him sooner than anticipated when an old friend discloses a terrible crime. Some words and ideas I got down and wanted to share.Starts during "25 Acts." What goes on in between the lines of Law and Order SVU, centered on Olivia and Barba's growing relationship. Other relationships will bleed in, but they won't be the main focus of the fic.
Casey revealed in "Influence," that she was once engaged to a schizophrenic man, but he refused to take medication, and she eventually left him. The topic was mentioned again in "Blinded", when Olivia Benson accused Casey of letting her guilt over the experience cloud her judgment regarding schizophrenic sex offender Saul Picard.
It was revealed in early season 5 that Casey graduated from Harvard Law School and used to clerk for Judge Mary Clark.
She initially joined the Manhattan DA's office in the Investigations department in the White Collar division.
In the season 6 finale, "Goliath", she is a supporter for the Troops saying that her father was a door gunner on a Huey in Vietnam.
He was in 3 chopper crashes and received a Purple Heart, a U. military decoration awarded to members of the Armed Forces who have been wounded in action.