The man arrested in the killing of right-wing activist Charlie Kirk is not cooperating with authorities, but investigators are working to establish a motive for the shooting by talking to his friends and family, Utah Governor Spencer Cox said yesterday.
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 on Wednesday.
Mr Kirk, a staunch ally of US 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 65 km of Salt Lake City.
The killing fuelled fears of a spike in political violence in the US 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."
"He is not cooperating, but all the people around him were cooperating, and I think that's very important," the Republican governor said.
One person who is apparently talking to investigators is Mr Robinson's roommate, who was also a romantic partner, Mr Cox said, citing the FBI.
Mr Cox described the roommate as "a male transitioning to female," and said the roommate has been "incredibly cooperative."
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 Mr Robinson's legal representative.
Asked on CNN's 'State of the Union' 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.
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-LGBT 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 program at Dixie Technical College, part of Utah's public university system, was taken into custody at his parents' house, about 420 km southwest of the crime scene after a 33-hour manhunt.
Investigators search for motive
Relatives and a family friend alerted authorities that he had implicated himself in the crime, Mr Cox said previously.
While Mr 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 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.
The killing has stirred outrage among Mr Kirk's supporters and condemnation of political violence across the ideological spectrum.
Mr Trump has blamed "the radical left" for Mr Kirk's death, despite a lack of evidence, even as he and his allies have often invoked violent rhetoric against their opponents.
"The problem is on the left," Mr Trump told reporters yesterday.
"A lot of people that you would traditionally say are on the left ... (are) already under investigation."
Pennsylvania Governor Josh Shapiro, a Democrat who faced an arson attack in April, said Mr Trump had an obligation to lower the temperature.
"Violence transcends party lines - and the way to address it and have true peaceful debate is for leaders to speak and act with moral clarity. That needs to start with the President," he said on social media.
Mr Cox assigned some blame to social media, saying it has played a "direct role" in every political assassination attempt in recent years.
Mr Trump has credited Mr Kirk with driving young voters to conservatism. His Turning Point movement says it has more than 800 chapters across college campuses. Mr Kirk's widow on Friday said the movement's efforts would go forward.
A memorial event for Mr Kirk will be held on 21 September in Glendale, Arizona, his organisation said.
Read more: Charlie Kirk killing ignites bitter free speech debate
