PIERRE, S.D. (AP) — A federal appeals court has affirmed a Canadian man's conviction in the 1975 murder of a fellow American Indian Movement activist in South Dakota.

John Graham contended the trial court lacked jurisdiction because he is a Canadian citizen and that his extradition violated an extradition treaty between the U.S. and Canada.

But the 8th U.S. Circuit Court of Appeals on Friday rejected Graham's arguments.

Graham was convicted in 2010 and sentenced to life for taking part in the December 1975 murder of AIM activist Anna Mae Aquash. Prosecutors said Graham and two other AIM activists, Arlo Looking Cloud and Theda Clarke, killed Aquash because they suspected she was a government informant.

South Dakota Attorney General Marty Jackley calls the ruling "an important step toward justice" for Aquash and her family.