Prosecutors dropped federal charges against one of two men accused in the 1975 slaying of a fellow American Indian Movement activist on a South Dakota reservation.

John Graham and Richard Marshall were charged in federal court with killing or aiding the murder of Annie Mae Aquash on the Pine Ridge Indian Reservation. U.S. District Judge Lawrence Piersol on Wednesday agreed to throw out the indictment against Graham after a request from prosecutors. Graham still faces state charges.

Graham's lawyer, John Murphy, had argued that his client, who is from Canada's Yukon territory, could not be prosecuted in federal court because he is not considered an American Indian. The federal government has jurisdiction over American Indian-related crimes.

Murphy was not immediately available for comment Wednesday.

The federal trial for Graham and Marshall, of Rapid City, S.D., had been scheduled to start Feb 16 in Rapid City. Marshall has pleaded not guilty.

Federal prosecutors did not immediately return phone messages seeking comment.

South Dakota Attorney General Marty Jackley said Graham's initial appearance in state court is scheduled in Pennington County court Wednesday afternoon.

Graham is charged with one count of felony murder in relation to kidnapping, one count of felony murder in relation to rape and one count of premeditated murder.

State prosecutors said Graham and two other AIM members — Arlo Looking Cloud and Theda Clarke — drove Aquash from Denver to Rapid City, where she was held against her will and questioned about whether she was an informant. Prosecutors have said she was not working with the government.

State prosecutors allege that Graham raped Aquash at the apartment of Thelma Rios and later fatally shot her near Wanblee, 86 miles east of Rapid City.

Rios is charged in state court with one count of felony murder in relation to kidnapping and one count of premeditated murder. She has pleaded not guilty.

Looking Cloud was convicted of murder in 2004 for his role in Aquash's death and sentenced to life in prison.