The breaking news was announced by US President Donald Trump on a morning television show.

“I think with a high degree of certainty, we have him,” said Trump on the sofa of Fox & Friends on Friday in New York City. “In custody.”

“Essentially, someone that was very close to him turned him in.”

It was Trump, too, who first announced that his political ally, Kirk, had died after he was shot in the neck while hosting an outdoor event attended by about 3,000 people at Utah Valley University on Wednesday.

At a news conference on Friday morning, officials identified the person in custody as 22-year-old Tyler Robinson.

The suspect lives in St George, Utah, near Zion National Park, about 250 miles (400km) south-west of the campus where Kirk was shot, BBC Verify has found.

According to the BBC’s US partner CBS, two law enforcement sources said the suspect’s father had recognised his son from images circulated by the FBI.

The sources added that the 22-year-old had confessed to his father, who urged him to turn himself in.

After the suspect said he would rather commit suicide than surrender, the father called a youth pastor who is a family friend.

The father and the pastor tried to calm down the suspect. The pastor, who also serves as a court security officer, called the US Marshals, who detained the suspect.

Utah Governor Spencer Cox said surveillance video shows the suspect arriving on the university campus in a grey Dodge Challenger at 08:29 local time (14:29 GMT) – nearly four hours before the shooting.

The governor told journalists that investigators had interviewed a family member who said the suspect had become more political in recent years.

Cox said: “The family member referenced a recent incident in which Robinson came to dinner prior to September 10, and in the conversation with another family member, Robinson mentioned Charlie Kirk was coming to UVU.”

There was a mention of how “Kirk was full of hate and spreading hate”.

Cox said investigators had also spoken to a roommate of the suspect who had shown them messages with an account named “Tyler” on the messaging app Discord.

The messages referred to a need to retrieve a rifle from “a drop point” and the rifle being left in a bush, wrapped in a towel.

The FBI said on Thursday they had found the suspected murder weapon – an imported Mauser .30-06 bolt action rifle – wrapped in a towel in a wooded area near campus.

Cox told reporters that inscriptions had been found engraved on casings recovered with the rifle, which had a scope mounted on top of it.

The inscriptions included “hey fascist! CATCH!” and “O Bella ciao, Bella ciao, Bella ciao, Ciao, ciao!” and “If you read This, you are GAY Lmao”.

Bella ciao means “goodbye beautiful” in Italian. It is also the title of a song dedicated to the Italian resistance who fought against the occupying troops of Nazi Germany.

The Utah governor said he was not aware of any potential further arrests in the investigation.

State prosecutors said they plan to file formal charges next Tuesday.

He is accused of aggravated murder, obstruction of justice, and felony discharge of a firearm, according to a Utah County Sheriff inmate booking sheet, obtained by the BBC.

FBI Director Kash Patel told reporters the crime scene was large, but had been processed quickly and forensic evidence had been recovered.

He said the first federal agents had arrived on the scene some 16 minutes after Kirk was shot.

“Just last night, the suspect was taken into custody at 10pm local time,” Patel said, capping a 33-hour manhunt.

The FBI director said his agents had been sifting through 11,000 leads.

The arrest came after the FBI released grainy pictures of a “person of interest” wanted for the shooting.

He was wearing sunglasses, Converse shoes and a “distinctive” long-sleeved black top featuring an American flag and an eagle.

After shooting Kirk from a rooftop, the suspect dropped from the side of the building and ran.

As he climbed down off the edge of the roof, he left palm impressions where forensic experts went to collect DNA.

He also left a shoe print that indicated he was wearing Converse shoes, similar to those worn by the suspect in the surveillance images.

After dropping off the building, CCTV showed the man moving across a grassy area before entering traffic.

He crossed the street into a wooded area, where the firearm believed to have been used in the shooting was later found.

On Wednesday, Patel said another potential suspect had been briefly detained for questioning before being released.

Another person – seen in viral videos on social media – was taken into custody immediately after the shooting, but was determined not to be the gunman.