The FBI posted a photo of a person of interest in the shooting death of Charlie Kirk whom it is asking the public to help identify.
Police also said on Thursday they have recovered the weapon they believe was used in the fatal shooting of the right-wing influencer and have"good video" of a potential suspect.
A high-powered, bolt-action rifle was recovered in a wooded area after the shooting at Utah Valley University, Robert Bohls, FBI's special agent in charge in Utah, said.
Beau Mason, Utah Department of Public Safety commissioner, said authorities are interested in pursuing a person who was captured on video. Mason said the person "blended in well" in a college campus setting, with respect to their age and appearance.
Officials have chosen not to release the video yet, but said they may be open to reconsidering that choice as the investigation proceeds.
FBI Director Kash Patel on Wednesday initially said on social media that a"subject" had been taken into custody, only to later say that the person had been released after being questioned.
Shooter may have accessed roof
Kirk, a right-wing activist and close ally of President Donald Trump who played an influential role in rallying young Republican voters, was shot around 12:20 local time in Orem, Utah, in what the state governor called a political assassination, even as a suspect has not been formally identified.
Trump said on Thursday he would award Kirk the Presidential Medal of Freedom, the highest civilian honour in the U.S., a day after calling him a"martyr for truth and freedom."
WATCH l Recap of Wednesday's developments in Kirk shooting probe: 
Charlie Kirk shot dead while speaking at Utah university
September 11
U.S. conservative commentator Charlie Kirk was shot and killed Wednesday during a public appearance at a university in Utah. He was 31.
Vice-President JD Vance and his wife, Usha, were set to visit with Kirk's family in Salt Lake City. Kirk was married, and a father to two small children.
Authorities previously said Kirk was killed with a single shot from a rooftop on Wednesday. They believe the suspect then jumped off the roof and fled into a nearby neighbourhood.
It is somewhat unusual, especially in an age of personal cellphones and abundant surveillance cameras, for a suspect in a public shooting of a notable figure in the U.S. to remain a fugitive for several hours. The manhunt for James Earl Ray — convicted in Martin Luther King's 1968 killing — was an exception, spanning two months and four countries other than the U.S., including Canada.
The 31-year-old Kirk personified the pugnacious, populist conservatism that has taken over the Republican Party in the age of Trump. Kirk launched his organization, Turning Point USA, in 2012, targeting younger people and venturing onto liberal-leaning college campuses where many Republican Party activists were nervous to tread.
Kirk identified as a Christian conservative and was an unabashed supporter of expansive gun-owning rights. He often made statements that his critics said were racist, homophobic or transphobic.
Utah Valley is also just a few kilometres away from Brigham Young University, which is owned by the Church of Jesus Christ of Latter-day Saints, known widely as the Mormon church.
Utah is one of 14 states that allow some level of concealed carry of firearms on public college and university campuses, and the first to do so.
The circumstances of the shooting drew renewed attention to an escalating threat of political violence in the United States that, in the last several years, has cut across the ideological spectrum. The assassination drew bipartisan condemnation, but a national reckoning over ways to prevent political grievances from manifesting as deadly violence seemed elusive.
