OREM, Utah (TNND) — The rifle that federal authorities believe was used in the fatal shooting of political activist Charlie Kirk contained ammunition engraved with expressions of transgender and antifascist ideology, according to an internal law enforcement bulletin obtained by The Wall Street Journal.

The 31-year-old co-founder and CEO of the conservative youth organization Turning Point USA was assassinated on Wednesday while hosting his American Comeback Tour at Utah Valley University.

In the shooting that officials called a "targeted attack," Kirk was shot in the neck in broad daylight while allegedly discussing transgender shooters. Videos showed stunned attendees running away and screaming as Kirk reached up to touch his neck while blood gushed from the left side.

It was reported that an older-model .30 caliber bolt-action rifle was found wrapped in a towel with a spent cartridge still in the chamber. Three unspent rounds were also in the magazine, with more writing on them.

The FBI released photos of a person of interest on Thursday in connection with the shooting as investigators ask the public for more information and offer a reward of up to $100,000.

Photos show a person wearing a hat, sunglasses and a long-sleeve black shirt.

Utah Department of Public Safety Commissioner Beau Mason said the shooter appeared to be of "college age" and is believed to have blended in on the university campus.

Robert Bohls, special agent in charge of the FBI’s Salt Lake City field office, added that footwear impressions, a palm print, and forearm imprints will also be analyzed by the FBI. Officials said they walked through the woods and secured it and the community is not at risk.

Mason said authorities were able to track the movements of the shooter, who arrived on campus at 11:52 a.m.

We have tracked his movements onto the campus, through the stairwells, up to the roof, across the river to a shooting location," Mason explained. "After the shooting, we were able to track his movements as he moved to the other side of the building, jumped off of the building and fled off of the campus into a neighborhood.

The FBI and DPS are co-leading the investigation in unison with the Utah County Attorney's Office, the Utah County Sheriff's Office and local police departments.