Which character became SVU's ADA after Rafael Barba left?

Peter Stone became SVU’s ADA after Rafael Barba left the position.

Stone arrives when District Attorney Jack McCoy appoints him as special counsel in “The Undiscovered Country,” where he prosecutes Barba after Barba is charged over the death of a terminally ill child. Barba is ultimately acquitted, but the case leaves him traumatized and leads to his resignation. Stone then takes over as the assistant district attorney overseeing Manhattan SVU.

Peter Stone was portrayed by Philip Winchester and was already part of the wider Dick Wolf television universe. He was introduced in Chicago P.D. and served as the central prosecutor in Chicago Justice before moving into SVU’s courtroom world. His family connection also links him to the original Law & Order: he is the son of former Executive Assistant District Attorney Ben Stone.

Michael Cutter and David Haden held other prosecutorial roles in the franchise, while Sonny Carisi first served as an SVU detective. Carisi later becomes an ADA, but he was not the immediate successor to Barba.