Man ordered to stand trial for shooting, killing of peaceful protester at 'No Kings' protest

SALT LAKE CITY — Volunteers for the security team at the June 14, 2025 "No Kings" protest testified about seeing a man they considered as suspicious, learning that man had a gun and then hearing three shots fired.

Those shots came from another volunteer for the security team, according to testimony at Tuesday's preliminary hearing, and one of them caused the death of Afa Ah Loo.

Matthew Scott Alder was ordered to stand trial on Tuesday for manslaughter, a second-degree felony.

Third District Judge Derek Williams ruled after hearing multiple witnesses testify that there is enough evidence that him firing the gun led to someone else's death and that he acted recklessly to go to trial. The judge clarified that at this point he is required to take all inferences in favor of the state, and is not supposed to consider whether witnesses or alternate theories are credible.

He said there was evidence there were three or four people between where Alder was firing and where the suspicious man, Arturo Gamboa, was standing.

Ah Loo, 39, was a recent U.S. citizen and Samoan fashion designer. His wife filed a lawsuit against the rally organizers and the accused gunman in March, claiming that Alder was an "untrained volunteer" who fired into a crowd without "respect for the sanctity of life."

Accounting for the bullets

Alder's attorney, Neal Hamilton, said he pleaded not guilty.

Hamilton argued new evidence from Friday that a gate box on a building had been hit as well means that each of the three rounds is accounted for, suggesting that something had intervened, moving a bullet to go at a different angle. He claimed one round hit Gamboa's side, one hit his gun and the other the gate box, meaning one of those three may have ricocheted and hit Ah Loo.

"All the evidence suggested that he was firing at his target, which is Mr. Gamboa," Hamilton argued.

He claimed that there may be an argument that Alder acted negligently, but not recklessly. The attorney said at this point in the case Alder can't claim self defense, but they would "absolutely" raise that claim later on in the case.

Deputy Salt Lake County attorney Josh Graves disagreed, arguing that Gamboa's firearm was right by his side and the same bullet likely hit his body and his gun. He said the lack of scratch marks, flattening or indentations on the bullet that hit Ah Loo makes it less likely that it hit something else.

Because Ah Loo was about 160 feet away from Alder, he said just a slight angle change in the gun could make a large difference in where it is aimed that far away.

Graves argued that Alder should have known, especially when shooting in a large crowd, that a backstop is of "vital importance," and that each shot should be a conscious decision.

Salt Lake City Police officer Bradley Shupe testified on Tuesday that cell phone video of the scene showed Ah Loo fall to the ground after the third shot was fired.

He said that the bullet that was found during Ah Loo's autopsy hit his temple and stopped at the back of his skull. When it was recovered, it looked "nearly pristine," which the officer claimed was unusual.

Shupe said it was possible that round had hit something else before ricocheting and hitting Ah Loo, but Derek Mears, a firearms expert with the Salt Lake City Police Department, testified he would expect to see more damage if it had struck something else first.

Firsthand witnesses

Richard Whitney organized the security team and said he assigned Alder with Nathan Bergstrom to the same area, knowing Bergstrom wasn't carrying a firearm, and Alder was. He assigned volunteers on the security team in pairs stationed around the march.

He said multiple people were legally carrying guns at the protest and other people were dressed anonymously in all black with face masks.

Whitney said he heard a voice on their radios saying "gun, AR-15," and another voice say they saw a "confederate flag black block," meaning someone dressed in all black with a Confederate flag. Those two reports, the team members testified, were about Gamboa. Just a little bit later, he heard "gun, gun, gun," and then gunfire. He tried to get people to cover and then moved toward where he thought the sounds happened.

Bergstrom testified that he had fallen back and saw Gamboa "fishing in a bag" in an alleyway, later seeing a rifle with a magazine. The man was acting "more than suspicious."

"I thought it was somebody that was about to commit a mass shooting," he said.

He testified that he saw the man run toward the street carrying the gun in a "ready, low position," pointed down and near his shoulder, and saw it come up but was not sure if it was pointed at someone. Bergstrom saw two other security members responding, telling Gamboa to drop his gun.

After hearing the gunshots, he said Gamboa ran up the street and headed towards a parking garage.

He went toward State Street and saw Ah Loo and called for a medic and encouraged calling officers as well.

Aaron Ferdig, another safety team member who had moved into that area, also said Gamboa was "extremely suspicious" when he ducked into the alleyway, and it appeared he was trying to assemble something. He also testified that he was worried about a mass shooting. Ferdig said he pulled out his gun worried that it was an "active, deadly threat."

Alarming but lawful

After going over video of the incident in his testimony, Shupe testified about responding to the "fairly chaotic" scene and went over video footage that also showed Gamboa going into an alley and dressed in dark clothing. He also testified about video that showed Gamboa taking off his mask and sweatshirt after the shooting and walking past multiple officers trying to fit into the crowd.

The officer testified that another person saw a rifle sticking out of his backpack, took it away from Gamboa and signaled to officers who took him into custody.

Salt Lake City District Attorney Sim Gill declined to file charges against Gamboa. He said although Gamboa's actions could be perceived as alarming, he was lawfully permitted to carry the rifle, and there is no evidence he violated any law.

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