Actually, rifles are used. Five, if I remember aright...four with bullets and one with a blank, preloaded and then mixed up by someone who didn't do the loading. Utah, with a Mormon majority, originally believed in the idea of "blood atonement." The LDS Church tossed this idea along with polygamy, but there may still be (probably are) those in Utah who believe it and want to show their "repentance and salvation" by shedding their blood.

I guess it beats Saudi Arabia's beheading and crucifixion as death penalties....