Charlie Kirk's alleged killer is "not co-operating" with authorities and has not confessed to carrying out the shooting, Utah's governor Spencer Cox has said.

Suspect Tyler Robinson, 22, was taken into custody some 33 hours after Kirk, a 31-year-old right-wing activist, was shot dead in Orem on Wednesday.

Cox, a Republican, told several Sunday morning shows that investigators were still trying to establish a motive but people around Mr Robinson were co-operating.

Kirk was speaking at Utah Valley University at an open-air event held by Turning Point USA - the organisation he co-founded - when he was hit in the neck by a single bullet.

The event was part of the American Comeback Tour, which was a speaking engagement that took him to several college campuses throughout the US.

Cox previously told the Wall Street Journal that Mr Robinson, a Utah native, was "deeply indoctrinated with leftist ideology".

When questioned on it during CNN's State of the Union programme on Sunday, he said the information was offered by the suspect's friends and family.

The governor said among those co-operating with authorities was Mr Robinson's roommate, who is also his partner.

He said the partner was currently "transitioning from male to female", but when asked by CNN, said that authorities do not yet know if that is relevant to the investigation.

Cox added that the partner did not have any knowledge about the alleged shooting, had been "incredibly co-operative" and was working with investigators "right now".

The governor was also asked about a New York Times report alleging Mr Robinson had spoken to others after the shooting via the Discord messaging platform, including allegations that he joked about being the gunman.

His "doppelganger," he wrote, was trying to "get me in trouble", according to messages seen by the Times.

Cox told ABC News: "All we can confirm is that those conversations definitely were happening, and they did not believe it was actually him.

"It was, it was all joking until, until he, you know, until he admitted that it actually was him."

Mr Robinson was arrested on Thursday night after surrendering to police.

An affidavit from the state of Utah confirms that Mr Robinson was arrested on suspicion of the crimes of aggravated murder, felony discharge of a firearm, and obstruction of justice.

He is currently being held without bail at Utah County Jail.

"We're interviewing all kinds of people - everyone that knows him - and trying to learn more about what the motive actually was," Cox said.

Following Kirk's death, Cox has been prominent in calling for unity in a bid to ease political tensions, and has made repeated comments criticising social media.

He previously called social media a "cancer" and told CNN the US had "to get phones out of the classrooms" and better efforts to hold platform owners to account.

He called Kirk's shooting a "direct assault on America" and said Americans needed to "look in the mirror and decide, are we going to try to make it better, or are we going to make it worse?"

Kirk's widow, Erika, on Saturday gave a tearful address in which she thanked first responders for their efforts and vowed that her "husband's voice will remain".

A memorial service will be held on 21 September at the 60,000-seat State Farm Stadium in Arizona, the state where Kirk lived with his wife and two children.

Kirk, a controversial figure in US politics, was one of the highest profile right-wing activists in the US and a trusted ally of US President Donald Trump.

Turning Point USA aimed to spread conservative ideals at liberal-leaning US colleges, and played a key role in getting people to vote for Trump and other Republican candidates in the election last year.

Kirk was a strong supporter of gun rights, vehemently opposed abortion, was critical of transgender and gay rights and promoted false claims about Covid-19.

His supporters said he was relatable and understood their concerns. But his views drew fierce liberal criticism, with his detractors calling his comments deeply offensive to some minority groups, including LGBT people and Muslims.