Mr Cox said the accused gunman, Tyler Robinson (22) would be formally charged tomorrow. He remains in custody in Utah.
Investigators have yet to piece together why Mr Robinson allegedly scaled a rooftop at Utah Valley University during an outdoor event and shot Mr Kirk in the neck at long range last Wednesday.
Mr Kirk, a staunch ally of president Donald Trump and co-founder of the conservative student group Turning Point USA, was killed by a single rifle shot during the event attended by 3,000 people in Orem, about 65km south of Salt Lake City. The killing has sparked new-found fears of a spike in political violence in the United States and an ever-deepening divide between the left and the right.
Mr Robinson has not confessed to investigators, Mr Cox told the ABC programme This Week.
President Donald Trump shakes hands with moderator Charlie Kirk, during a Generation Next White House forum at the Eisenhower Executive Office Building on the White House complex in Washington, Thursday, March 22, 2018. Photo: AP
“He is not co-operating, but all the people around him were co-operating, and I think that’s very important,” the Republican governor said.
One person who is apparently talking to investigators is Robinson’s roommate, who was also a romantic partner, Mr Cox said, citing the FBI.
This photo released by the Utah Governor’s Office on Friday, September 12, 2025, shows Tyler Robinson. Photo: AP
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Mr Cox described the roommate as “a male transitioning to female” and said the roommate has been “incredibly co-operative”.
Reuters has not been able to locate the roommate, or representatives for the roommate, to seek comment. Reuters could not determine who is serving as Robinson’s legal representative.
Asked on CNN’s State of the Union programme whether the roommate’s gender identity is relevant to the investigation, Mr Cox said: “That’s what we’re trying to figure out right now … It’s easy to draw conclusions from that, and so we’ve got the shell casings, other forensic evidence that is coming in – and trying to piece all of those things together.”
Investigators found messages engraved into four bullet casings, which included references to memes and video-game in-jokes. An affidavit filed by authorities in the case described these messages.
One of the inscriptions, according to the affidavit, read: “hey fascist CATCH” followed by a combination of directional arrows, an apparent reference to a sequence of button presses that unleashes a bomb in a popular video game.
A tribute to Charlie Kirk is shown on large screens at a sporting event (Wade Payne/AP)
Another casing, according to the affidavit, read, “If you read this, you are GAY lmao,” short for “laughing my ass off”.
Mr Kirk’s charged rhetoric, which often involved anti-LGBTQ+ and anti-immigrant comments, attracted legions of conservatives, but also engendered strong feelings from liberals and drew widespread criticism.
Mr Robinson, a third-year student in the electrical apprenticeship programme at Dixie Technical College, part of Utah’s public university system, was taken into custody at his parents’ house, about 420km south-west of the crime scene after a 33-hour manhunt.
Relatives and a family friend alerted authorities that he had implicated himself in the crime, Mr Cox said.
State records show Mr Robinson was a registered voter but not affiliated with any party
While Robinson was raised by religious parents in a deeply conservative region of the state, “his ideology was very different than his family”, Mr Cox said yesterday on NBC’s Meet the Press programme, without going into specifics.
State records show Mr Robinson was a registered voter but not affiliated with any political party.
A relative told investigators that Mr Robinson had grown more political in recent years and had once discussed with another family member their dislike for Mr Kirk and his viewpoints, according to the arrest warrant affidavit.
Mr Robinson was “not a fan” of Mr Kirk’s, Mr Cox said yesterday.
The killing has stirred outrage among Mr Kirk’s supporters and condemnation of political violence from some across the ideological spectrum.
Many Republicans, including Mr Trump, have been quick to lash out at the political left, accusing liberals of fomenting anti-conservative vitriol that would encourage a kindred spirit to cross the line into violence – even as the president and his allies have often invoked violent imagery against their opponents.