Officials announced formal charges against conservative speaker Charlie Kirk’s alleged assassin on Tuesday.

Tyler Robinson is being charged with several counts, including aggravated murder. 

Authorities allege that 22-year-old Tyler Robinson fired a single rifle shot from a rooftop sniper position, striking Kirk in the neck last Wednesday on the campus of Utah Valley University in Orem, about 40 miles south of Salt Lake City.

Kirk was delivering a speech to a crowd of roughly 3,000 attendees when he was shot. He died later that day at a nearby hospital.

While investigators have yet to disclose a motive, Kirk’s supporters, including his wife Erika Kirk, have portrayed him as a martyr for their movement. Kirk, 31, was the co-founder and leader of the conservative student organization Turning Point USA and a close ally of President Donald Trump.