Utah judge finds probable cause for manslaughter charge against protest safety volunteer

In a full-day hearing, Third Judicial District Judge Derek Williams determined that the Salt Lake County District Attorney’s Office had established probable cause to charge Matthew Alder, a volunteer on the protest’s safety team, with manslaughter. Alder fired three rounds during the June 14, 2025 No Kings protest in downtown Salt Lake City, believing a man in a ski mask and rifle, Arturo Gamboa, was about to open fire on the crowd.

One shot struck and killed protester Arthur “Afa” Ah Loo, and another grazed Gamboa’s abdomen; Gamboa was later apprehended. Defense counsel argued the fatal bullet could have been a ricochet, citing new forensic evidence, but Deputy District Attorney Josh Graves maintained Alder’s gunfire was reckless. Witnesses described a tense atmosphere with agitators and counter-protesters, and safety team members who, despite being urged not to arm themselves, carried handguns. The case is set for a pre-trial conference on Dec. 11.