- The Salt Lake County District Attorney's Office says UHP trooper legally justified in deadly shooting.
- Trooper Mower shot Mousavi after being rear-ended and threatened with a knife on I-15.
- Mousavi has prior interaction with authorities before shooting.
SALT LAKE CITY — A Utah Highway Patrol trooper who fatally shot a Sandy man armed with a knife after being rear-ended on I-15 by the man was legally justified in shooting him, the Salt Lake County Attorney's Office announced Friday.
But although Sim Gill acknowledges the trooper did what he was trained to do that day and no criminal charges will be filed, the fatal shooting is another tragic example of the need for better help for those in the community with mental health issues.
"There are just far too many of those intersections between those who are struggling with their mental health issues and the legal system," he said Friday,
On March 27, UHP trooper Caden Mower was in his marked patrol car on northbound I-15 near 4500 South just before 5 p.m. when he was hit from behind by a Nissan Versa.
Mower pulled over to the shoulder of the freeway, at which point the driver of the Nissan, Sayed Zeinullah Mousavi, 29, pulled up, made an obscene gesture with his hand, and drove off, according to Gill's final report.
The trooper initiated a chase with the Nissan until approximately 3500 South when the Nissan "stopped abruptly in the middle of I-15," according to the report. Mousavi "immediately" got out of his car while holding a knife in his right hand.
"(He) just kept coming at me. And then that's when I pulled the trigger," Mower told investigators, according to the report.
Mousavi "continued to come at trooper Mower with the knife. Trooper Mower yelled commands and then fired his weapon and the driver fell to the ground," the report states. Mousavi died at the scene. The investigation revealed that Mower fired 11 times.
Investigators learned that prior to his actions on the highway, Mousavi had been interviewed at his residence in Sandy by an FBI agent. He then drove away from his residence and was involved "in a vandalism incident to a parked UHP patrol vehicle at the UHP office in Murray," according to the report.
"The totality of the facts in this case, taken together with reasonable inferences about trooper Mower's decision to use deadly force, would likely cause a jury to determine that his use of deadly force satisfies the elements of the affirmative legal defense of justification," Gill concluded in his report. "Accordingly, we decline to file a criminal charge against him in this matter.
Mousavi was convicted in May of 2025 of making a threat of terrorism. He was sentenced to probation, and Gill said that when he was taking his medication, he was compliant and had successfully completed the terms of his probation.
But on that day, something about the FBI visit agitated Mousavi, Gill said. Although Gill says he does not know what the agent was making inquiries about, shortly after the agent left, Mousavi "swallowed a large amount of Adderall" — possibly believing it was a different medication - and became aggressive. Gill says that within 10 minutes, Mousavi's sister called the FBI agent to report what had happened, and within six minutes after that, the agent contacted Sandy police to let them know Mousavi was possibly suffering from a mental health crisis.
"To me, this is a tragic, tragic outcome. But I understand why the trooper (used deadly force). The family really tried to get help for him, was supportive of him. And I think it bears testament to how broken our mental health system is, because they are mourning the loss of a son, of a sibling. And I genuinely believe they really did everything they could," Gill said.
