Tyler Robinson, the 22-year-old Utah man accused of assassinating conservative activist Charlie Kirk, was charged on Tuesday with aggravated murder, a prosecutor announced, saying Robinson left behind his DNA on the trigger of the rifle that fired the fatal shot.

The charge means Robinson could face the death penalty if convicted of killing Kirk last week at Utah Valley University in Orem, about 40 miles (64 kilometers) south of Salt Lake City.

“The murder of Charlie Kirk is an American tragedy,” Utah County Attorney Jeff Gray said in announcing the charges. He said Robinson's DNA was found on the trigger of the gun used to kill Kirk.

Kirk was gunned down on Sept. 10 as he spoke with students and died soon after. Prosecutors allege Robinson shot Kirk in the neck with a bolt-action rifle from the roof of a nearby campus building.

A Utah Valley University police officer was watching the university campus crowd from an “elevated position” and identified the roof of the Losee Center as a potential position for a shooter, Gray said. The officer found evidence on the roof immediately, he said, and spurred officers to direct their attention to surveillance video leading to the roof.

Gray said Robinson’s DNA was found on the trigger of the rifle. He said Robinson discarded the rifle and clothing and asked his roommate to conceal evidence.

Robinson also was charged with felony discharge of a firearm, punishable by up to life in prison, and obstructing justice, punishable by up to 15 years in prison. He was scheduled to appear on camera for a virtual court hearing Tuesday afternoon.

It was unclear whether Robinson had an attorney who could speak on his behalf, and his family has declined to comment to The Associated Press.

Robinson was arrested late Thursday near St. George, the southern Utah community where he grew up.

Investigators have spoken to Robinson’s relatives and carried out a search warrant at his family’s home in Washington, Utah, about 240 miles (390 kilometers) southwest of where the shooting happened.

Kirk, a dominant figure in conservative politics, became a confidant of President Donald Trump after founding Arizona-based Turning Point USA, one of the nation’s largest political organizations. He brought young, conservative evangelical Christians into politics. His shooting raised fears about increasing political violence in a deeply polarized United States.