WAGNER, S.D. (AP) — The FBI says it’s investigating a stabbing death on the Yankton Sioux Indian Reservation. The agency says a suspect has been arrested in Tuesday evening’s stabbing in Wagner. The victim is identified as 54-year-old Isaac Primeaux. FBI agents continue to investigate the circumstances surrounding the stabbing with the assistance of state and tribal law enforcement officers. Once the investigation is complete, the case will be presented to the US Attorney’s Office in South Dakota for any charging decision.