Utah protest shooting suspect charged in death of innocent marcher

A crowd of about 10,000 people was marching through downtown Salt Lake City when three shots rang out, and Arthur Folasa Ah Loo, a 39-year-old fashion designer and father of two, fell dead. Prosecutors say the armed volunteer who fired, Matthew Scott Alder, believed he was stopping a looming attack on the crowd. The legal case now turns on whether that belief can shield him from criminal liability after a bystander was killed.

Ah Loo, known in the community as “Afa,” was taking video as he walked in the June 14, 2025 No Kings protest when he was struck. Prosecutors said Alder fired three times during the demonstration, killing Ah Loo with one shot and wounding the man Alder believed was the threat with another. That intended target, Arturo Roberto Gamboa, 24, was the man police said was carrying a rifle and was later arrested on a murder charge.

The shooting was chaotic and public, unfolding in front of a dense protest crowd at a moment when police and witnesses described fear over an armed man in the march. Salt Lake City police said at least three shots were heard. Alder, 43, of Murray, later told police he thought he saw a man ducking as he loaded his rifle and believed the man was about to carry out a mass shooting, according to prosecutors. But prosecutors said that even if Alder claimed self-defense or defense of others, firing into a crowd made his conduct reckless.

Salt Lake County prosecutors charged Alder with manslaughter, a second-degree felony, in December 2025, nearly six months after the shooting. Ah Loo’s widow, Laura Ah Loo, called the charge a significant first step and said the wait for an answer had been painful and frustrating. Her attorneys have also said they were preparing a civil lawsuit, underscoring how one burst of gunfire has moved from a criminal case into a broader fight over accountability, grief and public safety.

The case has already reached Utah’s Capitol. Lawmakers began citing the shooting as they pushed to clarify the state’s self-defense law, arguing that current law does not clearly spell out what happens when someone is justified in using force against an aggressor but accidentally kills or injures a bystander. Sen. Kathleen Riebe said she wanted a clearer path forward, and a Senate criminal justice committee advanced SB105 by a 4-1 vote.

At the center of the case is a question that reaches far beyond one Salt Lake City block: when an armed civilian acts on fear in a protest crowd, does the law stop at intent, or does it extend to the innocent person who pays the price?