The suspect in conservative activist Charlie Kirk's death investigation is still at large, officials have said.
Mr Kirk had been shot in the neck on Wednesday during an event at Utah Valley University.
Utah's Governor warned Mr Kirk's killing was a "political assassination" - but further details of the shooter are coming through slowly.
Officials went on to provide conflicting accounts as to whether the suspected shooter was in custody.
FBI Director Kash Patel said "a subject" was in custody, while local police officials said the shooter was at large.
Mr Patel later said: "The subject in custody has been released after an interrogation by law enforcement.
"Our investigation continues and we will continue to release information in interest of transparency."
Some footage has emerged appearing to show a dark shape on a rooftop opposite the stage on which Mr Kirk was speaking - sparking intense speculation online.
No official body has yet commented on the video clips.
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Utah law enforcement issues update on shooter manhunt - as FBI opens up special 'tip line'
Law enforcement in Utah have issued an update on their manhunt for Charlie Kirk's killer.
Authorities said the pair who were arrested then released in relation to the shooting have "no current ties" to the incident.
"This shooting is still an active investigation," Utah's Department of Public Safety said.
It added that the shooting was a "targeted attack," the department says, with the suspect believed to have fired the fatal shot from the roof of a building to the courtyard in which Kirk was addressing crowds.
Meanwhile, the FBI has opened a "digital media tip line" in a bid to find information about the shooting.
Charlie Kirk's last message to his followers: A call for change - and fury at 'savage monster' who killed Ukrainian Iryna Zarutzka
Charlie Kirk's final message to his followers on social media was a call for change following the death of Iryna Zarutzka, the Ukrainian refugee stabbed to death on a train in August.
"If we want things to change, it's 100 per cent necessary to politicize the senseless murder of Iryna Zarutska because it was politics that allowed a savage monster with 14 priors to be free on the streets to kill her," he wrote.
US Attorney General Pam Bondi has now unleashed a federal prosecution against Brown Jr.
The alleged killer, 34 and homeless, has a history of mental health problems, arrests and convictions. He had already been charged with first-degree murder in North Carolina.
Republican Congresspeople from North Carolina have now demanded the removal of a state judge who released Brown Jr.
READ THE FULL STORY ON THE FALLOUT OVER IRYNA ZARUTZKA'S DEATH HERE
Police begin door-to-door searches as killer STILL not found
The Utah Valley University campus itself is locked down, with heavily-armed officers roaming the area
|REUTERS
Police are going door-to-door in the area around the Utah Valley University campus in a bid to find Mr Kirk's killer, the BBC reports.
The campus itself is locked down, with heavily-armed officers roaming the area.
Police have barred anyone from entering the university itself.
Key details on Charlie Kirk shooting suspects as clock ticks in major manhunt
The clock is ticking on a major manhunt for the shooter who killed Charlie Kirk.
A man who was taken into custody in the immediate aftermath of Mr Kirk's death, 71-year-old George Zinn, was not the shooter, authorities revealed.
Another man who was taken into custody and questioned by police has now also been released.
Following Kash Patel's words earlier, the FBI is now working with local police to track down the killer - with Utah Governor Spencer Cox vowing the murderer may face the death penalty.
WATCH IN FULL: Donald Trump addresses America after Charlie Kirk's 'assassination'
Utah Valley University SHUTS until Monday after Charlie Kirk assassination
Utah Valley University has said its campus will be shut down until Monday September 14 in the wake of Charlie Kirk's killing.
"UVU campuses will be closed from September 11-14," a statement says. "All classes (in-person or virtual), campus events, and administrative operations will be suspended during this time. Please plan accordingly and make any necessary adjustments to your schedules."
PICTURED: Mourners gather across the US
PICTURED: Mourners bring flowers to a memorial for Charlie Kirk, who was shot and killed in Utah, outside Turning Point in Phoenix, Arizona
|REUTERS
Charlie Kirk compared to JFK as tributes pour in from across America
Tributes have poured in across America and beyond for Donald Trump ally and conservative activist Charlie Kirk after he was shot dead during an event at Utah Valley University.
US Health Secretary Robert F Kennedy has compared Mr Kirk to his uncle, John F Kennedy, writing: "Once again, a bullet has silenced the most eloquent truth teller of an era.
"My dear friend Charlie Kirk was our country's relentless and courageous crusader for free speech. We pray for [his wife] Erika and the children.
"Charlie is already in paradise with the angels. We ask his prayers for our country."
WATCH: Charlie Kirk's full GB News interview
RECAP: Charlie Kirk pronounced dead after being shot in the neck during university campus speech
Conservative activist Charlie Kirk died late on Wednesday evening after being shot in the neck during an event at Utah Valley University.
Mr Kirk, 31, was shot as he started to conduct a Q&A session with students - with highly graphic footage circulating online.
"A single shot was fired on campus toward a visiting speaker," the university said.
Mere minutes before the attack, Mr Kirk, a close Trump ally, had written on social media: "WE. ARE. SO. BACK. Utah Valley University is FIRED UP and READY for the first stop back on the American Comeback Tour."
But the President himself was later forced to confirm the 31-year-old had died.
“The great, and even legendary, Charlie Kirk, is dead”, Mr Trump wrote on social media.