BISMARCK, N.D. (AP) – A man accused of stabbing the Bureau of Indian Affairs superintendent on South Dakota’s Crow Creek Indian Reservation has pleaded guilty to attempted murder under a deal with prosecutors.

In return for Brian Iron Boulder’s guilty plea last week, federal prosecutors have dropped assault charges.

Iron Boulder could have faced 50 years in prison if convicted on all three counts he faced. Court documents indicate he now will face between 15  1/2 and 19  1/2 years when he’s sentenced Sept. 14.

Iron Boulder is a member of the Standing Rock Sioux tribe in the Dakotas. Authorities said he stabbed Patrick F. Duffy in the back with a knife on March 25. Duffy was in critical condition for a time but survived and returned to work about two months later.