Rare mounted albumen photograph, captioned: "Tasunke, Ota (alias Plenty Horse) The slayer of Lieut. Casey, near Pine Ridge, S.D...", by John C. Grabill, 1891. The 7" x 9" photo shows Plenty Horse with a blanket about his shoulders, standing and leaning upon a cannon. The photo is mounted to a page from a period military publication. Some marginal defects include a corner chip at lower-left and a 1/2" tear at right, a few light creases, else very good. PLENTY HORSES (Tasunka) (1869–1933) was a Sicangu (Brulé) Lakota from the Rosebud Indian Reservation. On January 7, 1891, eight days after the Wounded Knee Massacre, he shot and killed Army Lt. Edward W. Casey, commander of the Cheyenne Scouts (designated Troop L, Eighth Cavalry) in the Badlands of the Pine Ridge Indian Reservation. Plenty Horses – who was present at the Drexel Mission Fight the day after the Wounded Knee Massacre, was arrested for the murder and his case went to trial. His defense was he shot and killed Casey as an effort to redeem himself in the eyes of his people after having spent five years at the Carlisle Indian School learning the ways of the white man. He returned in time to be present on the reservation during the massacre. He was acquitted as it was determined that a "state of war" existed between the Indians and the U.S. - which also absolved the 7th Cavalry of blame for the Wounded Knee Massacre. JOHN C. H. GRABILL (1849-1903) was a prominent western photographer most remembered for his important images of the early Pine Ridge Indian Reservation, the Sioux Indians, the aftermath of the Wounded Knee Massacre.