Boulder police arrested an 18-year-old Thornton man Monday morning on suspicion of killing one CU Boulder student and wounding another in a Halloween night shooting on University Hill.
The Boulder County District Attorney’s Office has charged Omar Perez with first-degree murder, first-degree assault and attempted first-degree murder, all alleging “extreme indifference to the value of human life,” according to police. While police say additional people could face charges in connection with the shooting, they believe Perez was the only shooter.
Both victims were 19-year-old men and CU Boulder students. One was shot in the neck and died early Sunday, Nov. 1. The other was shot in the leg and remained hospitalized Monday. He was in critical condition Sunday morning; police confirmed Monday that his condition had not worsened.
The killing was Boulder’s first homicide of 2026, Police Chief Stephen Redfearn said at a Sunday news conference.
The shooting occurred around 11:30 p.m. at a home in the 700 block of Marine Street. Residents had been hosting a Halloween party earlier in the night, with a live band and an estimated 800 attendees. The party ended around 10 p.m., after police responded to a noise complaint at the residence. Hundreds of partygoers left the area, and a small group remained inside, according to police.
According to a police affidavit, the confrontation began when six people, including Perez, entered the Marine Street home. A witness told police they were there without an invitation, and a resident told police he did not know anyone in the group. A witness said the group became angry after being told to leave.
According to the affidavit, the group was walking out the front door when Perez turned around and pushed his way back into the house. Three other men attempted to follow him, but were stopped at the door. The door was closed with Perez still inside.
Fights broke out both inside and outside the house, according to the affidavit. One of the residents told police he grabbed Perez and walked him back to the front door, where Perez started firing a pistol, striking the two students.
The resident said he let go of Perez, and Perez ran out of the house.
The resident told police he did not know why the group was at his house. Perez is not a CU student.
Officers arrived within two minutes of receiving reports of the shooting and applied a tourniquet to one victim before both were taken to the hospital. The Boulder County Coroner’s Office will release the identity of the student who died.
Police are sharing photos and videos of people they are seeking to identify on their website, and are asking anyone who recognizes the individuals or has information about the shooting to call Boulder police dispatch at 303-441-3333 and reference case 26-10148. Witnesses can submit video and photo tips here.
The families of the two victims are requesting privacy.
Redfearn said Perez was arrested in coordination with Thornton police, Westminster police and the Adams County Sheriff’s Office.
“Everyone in our community deserves to feel safe and while I hope this arrest restores some measure of safety, I know it will never bring back the life of this young man or undo all the trauma victims have gone through,” he said. “I’m incredibly proud of our detectives and officers who have worked nonstop since late Saturday to find and arrest this suspect.”
District Attorney Michael Dougherty thanked law enforcement for their swift response in a statement.
“As the criminal prosecution gets underway, I promise you that our team will be relentless in the pursuit of justice,” he said.
