Orem (United States) (AFP) - Authorities announced Friday that they have taken into custody the person believed to have assassinated Charlie Kirk, a right-wing activist and close ally of President Donald Trump.

He was shot while speaking at an event on Wednesday at Utah Valley University (UVU), in the city of Orem, Utah.

Here is what we know so far.

- The suspect -

Tyler Robinson, 22, is in custody after his father and a friend helped turn him in late Thursday evening, Utah Governor Spencer Cox told a press conference.

He was detained in Washington County, the area where he lived with family, about 250 miles (400 kilometers) southwest of Orem, and near the famed Zion National Park.

Photos posted on social media by his mother, Amber, seem to show a close-knit family. He was the eldest of three boys. Neighbors told US media the family was Mormon.

Dixie Technical College said Robinson was in his third year of an electrical apprenticeship program, while Utah State University said he had attended one semester in 2021.

- The shooting -

Kirk, head of the country’s largest conservative youth movement, which he co-founded in 2012 at the age of 18, was speaking at around noon Wednesday when a shot rang out.

The 31-year-old collapsed with a neck wound, according to a graphic video clip which quickly spread across social media. Trump announced his death a few hours later.

Authorities say Robinson used a high-powered, bolt-action rifle, firing from the roof of a building up to 200 yards (185 meters) away from his target. They said the killer was lying prone, a position that can increase accuracy.

- The motive -

Robinson’s family said he “had become more political” in recent years and had discussed Kirk’s upcoming event at UVU, criticizing the conservative influencer, according to Cox.

He was registered to vote as unaffiliated to any political party.

Kirk was a hero to right-wingers and helped Trump build a large youth vote in his November presidential election victory. He was also a highly divisive figure, espousing hardline views on race, gender, and gun ownership.

Even his many critics often hailed Kirk’s willingness to debate, however. Kirk was on a speaking tour when he went to the Utah university.

While the shooter’s motive remains unclear, much attention has been focused on the inscriptions found on bullet casings found at the crime scene.

One cartridge had written on it, “Hey, fascist! Catch!” said Cox.

Another featured “Bella ciao,” apparently a reference to a World War II-era Italian anti-fascist song.

Other cartridges were marked with symbols and wording that appeared to be from the online gaming culture.

The United States has seen repeated shootings and assaults against politicians over the last decade, including two assassination attempts on Trump – in addition to a long history of political violence stretching back decades.

Mass shootings by typically young, disturbed men are also common, and powerful firearms are easily available.

- The political reaction -

Politicians on all sides quickly condemned the killing, many of them calling on Americans to heal growing divisions.

Trump’s first reaction on Wednesday was to blame “the radical left.” He toned his rhetoric down on Thursday and said that Kirk had been “an advocate of nonviolence.”

“That’s the way I’d like to see people respond,” he said.

Kirk is being treated as a national hero by the Trump administration.

Trump announced on Thursday he would posthumously decorate Kirk with America’s highest civilian honor, the Medal of Freedom.

The Republican president also told reporters that he would attend Kirk’s funeral.

Kirk’s coffin was transported to his home city of Phoenix on Vice President JD Vance’s official plane.