More than 24 hours after the fatal shooting of right-wing activist Charlie Kirk during an event at a university in the United States, there is still no suspect in custody.
Law enforcement agencies in Utah say they are investigating "multiple leads", while more images of the "person of interest" have been released.
US investigators said they have found the bolt-action rifle they believe was used to kill Kirk.
Kirk, a 31-year-old author, podcast host and close ally of US President Donald Trump, helped build the Republican Party's support among younger voters.
He was killed on Thursday AEST by a single gunshot as he gave a talk at a university in Utah in what Trump called a "heinous assassination".
Security-camera videos show a person going up stairwells to get onto a roof before firing at Kirk, the officials told a press conference.
Kirk, a staunch defender of gun rights, was answering an audience question about mass shootings when the bullet struck his neck. Audience members fled in panic.
Source: SBS News
Video footage released on Friday by the FBI showed a person it said was the shooter jumping down from a rooftop and fleeing the scene.
Images of the 'potential shooter' released
Security footage images shared by the FBI show the person wearing a black top, black sunglasses, and a dark baseball cap. The top appears to have an image of a bald eagle flying across a US flag.
The shooter appears to be of college age and "blended in well" on the campus, Utah public safety commissioner Beau Mason told reporters.
Utah state officials called the person in the photos "the potential shooter".
The shooter has not been publicly identified, but two US officials and a law enforcement source say they have identified the name of the person of interest, according to CBS News.
No arrest warrant has been issued yet.
The FBI offered a US$100,000 ($150,000) reward for information leading to the killer's arrest.
There have been more than 200 tips from the public, with Utah's Department of Public Safety saying "they keep coming in".
Weapon being analysed
Investigators found a "high-powered, bolt-action" rifle in a nearby wooded area and were examining that along with palm prints and footprints for clues.
On Thursday local time, with classes cancelled, the roof of the building on the otherwise deserted campus and the nearby woods were strung with yellow tape as investigators scoured them for evidence.
A report from the Wall Street Journal claimed that the ammunition found appeared to have been engraved with messages related to transgender and anti-fascist ideology.
Utah's Department of Public Safety said it was "not able to provide further details on the content of those inscriptions".
While Kirk was killed by a single shot fired from a distance of 160m, Mason said it didn't mean the suspect necessarily had a military background.
"Utah is full of hunters and avid outdoorsman riflemen. And that is an average shot. Not saying it’s easy, but it doesn’t necessarily require an expertise," Mason said.
He added that it was easy for the shooter to access the roof of the Utah Valley University building and open fire, as the building had open pathways and lacked locked doors.
After the shooting, security footage showed the suspected shooter jumping from the roof onto a grassy area, then fleeing to nearby woods where the weapon was found.
— With additional reporting by the Reuters news agency.
