Questions are mounting as the manhunt for Charlie Kirk's killer enters its third day following the release of new video of a person of interest .
In the latest video, which was played during a news conference with state and federal officials Thursday evening, the suspected gunman can be seen climbing down from the roof of a building on the campus of Utah Valley University where authorities believe he fired the fatal shot and fled rom the scene.
The FBI said it is offering a reward of up to $100,000 for information leading to the identification and arrest of the person responsible for Kirk's murder.
Utah authorities released photos of the person of interest in the shooting on Thursday in which the individual can be seen on steps while carrying a black backpack and wearing a shirt with what appeared to be an American flag print on it.
So far authorities have received more than 7,000 tips and leads and completed some 200 interviews, Utah Gov. Spencer Cox said.
Amid the manhunt for the shooter, officials said Thursday they are working "around the clock" to locate the person of interest, who is believed to be college-aged.
The FBI also said Thursday it has recovered what is believed to be the weapon used in the deadly shooting. A "high-powered bolt action rifle" was recovered in a wooded area near where the shooting took place, according to Salt Lake City FBI Special Agent in Charge Robert Bohls.
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The rifle is an older model imported Mauser .30-06 caliber bolt action rifle wrapped in a towel, multiple law enforcement sources told ABC News. The location of the firearm appears to match the suspect's route of travel, the sources said.
The spent cartridge was still chambered and three unspent cartridges contained wording on them expressing what some law enforcement officials described as "transgender and anti-fascist" writing, according to preliminary information shared with agencies. It's unclear what that means and authorities are still working to determine the meaning or whether the markings were intended as misdirection for investigators.
Officials said that at 11:52 a.m. on Wednesday, the suspect arrived on the Orem campus and then proceeded to travel through the stairwells up to the roof of a building near the where the outdoors event was taking place, before the shooter fired down at Kirk, Utah Department of Public Safety Commissioner Beau Mason said on Thursday.
Kirk was hit by a single shot at approximately 12:20 p.m. and taken to a hospital, where he was pronounced dead, authorities said.
After the shooting, the suspected shooter traveled to the other side of the building, jumped off and fled off-campus into a neighborhood, Mason said. Officials are working through nearby neighborhoods, contacting people with doorbell cameras and speaking to witnesses to identify any leads, Mason said.
"I want to make it crystal clear right now to whoever did this, we will find you. We will try you, and we will hold you accountable to the furthest extent of the law," Cox said during a press briefing Wednesday, calling the fatal shooting a "political assassination."
He said state officials are already moving to pursue the death penalty if the case goes to trial.