An older model .30-caliber shotgun was allegedly the murder weapon in the killing of 31-year-old conservative activist Charlie Kirk, who was found by FBI agents in the woods near Utah Valley University.

According to the Wall Street Journal, the gun was found wrapped in a towel and had one spent cartridge still in the chamber and three unused cartridges in the magazine. Engraved slogans in support of transgender and anti-fascist ideology were found on the ammunition, according to an internal law enforcement release and supported by a person familiar with the investigation.

The investigation continues as authorities review findings and clues that may shed light on the shooter’s motives.

At the time he was fatally shot, Charlie Kirk was on the Utah University stage, talking with a student about mass shooting incidents involving transgender people.

Kirk, who was sitting under a tent and wearing a white short-sleeved T-shirt with the word “Freedom” and dark pants, answered questions from the audience, was attacked when an audience member took the microphone to challenge him. “Do you know how many trans Americans have been perpetrators in mass shooting incidents in the last 10 years?” he asked him.