Tyler Robinson denies aggravated murder, a capital offence in Utah, and six other charges in connection with the shooting of Kirk at a campus event on 10 September 2025.
The 23-year-old is charged with aggravated murder, a capital offence in Utah, and six other counts.
The police officer shot Glenwood Earl Pysher, 22, as he walked towards him with hands up, say prosecutors.
Prosecutors say the 17-year-old from North Carolina also published a manifesto from the two teenage shooters in the 18 May attack.
The attack left five injured outside a halls of residence, and the suspect was not a student there, say police.
"I shot Mr Thompson in Manhattan and he died," the 28-year-old said after pleading guilty to charges of stalking resulting in death.
Families grieved on Monday as they remembered the three people killed in a shooting at a food festival.
One suspect is in custody, while a second is being sought and a third is thought to have died at the scene, court documents show.
Two people were killed and five injured on Sunday night in a shooting at the Seattle Center.
