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 on Sunday.
Cox said the accused gunman, Tyler Robinson, 22, would be formally charged on Tuesday. He remains in custody in Utah.
Investigators have yet to piece together why Robinson allegedly scaled a rooftop at Utah Valley University during an outdoor event and shot Kirk in the neck at long range on Wednesday.
The killing ushered in newfound fears of a spike in political violence in the United States and an ever-deepening divide between the left and the right.
Robinson has not confessed to investigators, 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 Robinson's roommate, who was also a romantic partner, Cox said, citing the FBI.
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 Sony's hit video game Helldivers 2.
'Leftist beliefs'
Cox, who has earned plaudits for urging Americans to lower the toxic political temperature, made the rounds of US networks Sunday and told NBC talk show "Meet the Press" that investigators believed Robinson had embraced leftist beliefs.
"There clearly was a leftist ideology with this — with this assassin," Cox said.
He said such information about Robinson, who has not been cooperating, was told to investigators by "people around him, from his family members and friends."
Cox told CNN that they are still figuring out whether the gender identity of Robinson's partner played a role in the killing of Kirk.
The identity of Robinson's partner has drawn fury from right-wing figures.
