Court documents allege that Tyler Robinson, 22, confessed in text messages to killing conservative activist Charlie Kirk during a Utah Valley University event.

Robinson’s roommate found a note at their apartment outlining his plan, and later received texts in which Robinson admitted to the shooting, discussed hiding his grandfather’s rifle near campus, and said he had planned the attack for over a week.

Robinson surrendered after his parents recognized him in surveillance photos, CBS News has reported.

He faces multiple charges, including aggravated murder, and Utah prosecutors plan to seek the death penalty.