Utah News Dispatch
Prosecutors charge armed volunteer with killing bystander at Utah No Kings protest
First responders tend to a man injured in a shooting at the “No Kings” protest in Salt Lake City on Saturday, June 14, 2025. (Photo by Spenser Heaps for Utah News Dispatch)
The armed protest volunteer accused of killing an innocent bystander in June told police he intended to neutralize a threat. Now, almost six months later, prosecutors say he’s the one responsible for the violence.
The Salt Lake County District Attorney’s Office filed a charge Wednesday of manslaughter, a second-degree felony, against Matthew Scott Alder, 43, of Murray.
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Alder fired three times during the No Kings protest in Salt Lake City on June 14, Gill said. One shot killed protester Arthur “Afa” Ah Loo and another wounded Alder’s intended target, a man carrying a rifle.
“While you may have a right to use lethal force, that doesn’t mean that lethal force can be used in a reckless manner,” Salt Lake County District Attorney Sim Gill told reporters Wednesday in announcing the criminal charge.
Ah Loo, a father of two and fashion designer from Clearfield, was taking video of fellow protesters marching in downtown Salt Lake City when he was killed.
Alder told investigators he believed he saw a man “ducked down as he was loading his rifle” and thought he was about to commit a mass shooting, charging documents say. Alder then fired at the man, toward a crowd.
An attorney who previously represented Alder did not immediately return a request for comment.
Ah Loo’s widow, Laura Ah Loo, said in a news conference Wednesday the criminal charge represents “a significant first step in the right direction” and sets a precedent she hopes will lead to safer public gatherings in the future.
She said the months since her husband’s death “have been long, painful and deeply frustrating” as her family has waited for answers. She held back tears as she talked about her grief and said her husband was an incredible father.
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Her attorneys are preparing a civil lawsuit against Alder, said lawyer James McConkie. They’re also working to find out more about the protest organizers, McConkie said, including someone who applied for a Salt Lake City event permit under a fake name.
After the shooting, police did not initially arrest Alder, identifying him as a peacekeeper who was working with protest organizers at the event. Gill said he’s not asking for Alder to be jailed before trial because he doesn’t see him as a flight risk. Instead, Gill said he’ll request a summons ordering him to appear in court.
On the day of the protest, police did arrest Arturo Gamboa, the man who was carrying the rifle Alder saw, as Utah law allows, but did not shoot anyone.
Gamboa’s actions that day could be seen as “alarming and irresponsible conduct, by assembling an AR-15 under cover during a mass gathering,” Gill said, but he didn’t break any law.
Gill said assailants assume the risk of being killed in self-defense by their victims, but bystanders who do nothing to trigger the use of deadly force don’t take on the same risk simply because they were in the wrong place at the wrong time.
Gamboa spent almost a week in jail and was released without being charged with any crime. His attorney Greg Skordas has said his weapon was unloaded and pointing down when he was shot.
Gill confirmed Wednesday that his office is not filing criminal charges against Gamboa, saying there’s insufficient evidence he committed a crime.
Gill, a Democrat, noted state law permits people to openly carry guns in public spaces and called Utah’s self-defense law “robust,” saying together, those factors can leave innocent bystanders vulnerable to being shot.
Alder is not charged with shooting and wounding Gamboa in the torso, Gill said, because Utah law shields him from such liability.
If convicted in Ah Loo’s death, he faces up to 15 years in prison and a $10,000 fine.
Democratic state Reps. Verona Mauga and Jake Fitisemanu said the district attorney’s announcement brought complicated feelings of sorrow and anger, but also relief and hope.
“Our hearts are with Afa’s family and the whole Pacific Islander community, who have carried unimaginable grief since June,” they said in a statement. “We are grateful that we are finally seeing movement toward accountability.”
Mauga, a friend of Afa Ah Loo’s, said she’s in the early stages of crafting a bill that would restrict people from openly carrying rifles near protests and public events.
Utah’s overwhelmingly Republican Legislature has consistently rejected efforts to tighten gun laws. But Mauga, D-Salt Lake City, said she’ll ask her colleagues to consider the proposal anyway.
“Regardless of where it goes, I think the conversation is such an important piece,” Mauga said. “And that’s what we need to have right now, if we’re serious about public safety and preventing things like this from happening in the future.”
