Utah prosecutors said on Tuesday they will seek the death penalty for the suspect in conservative activist Charlie Kirk's assassination and revealed some of the evidence against him, including alleged text messages in which he appeared to confess to the crime.

"I had enough of his hatred," Tyler Robinson, 22, told his roommate and romantic partner when asked why he had committed the murder, according to transcripts of messages in court documents filed by prosecutors on Tuesday.

He is accused of firing the single rifle shot from a rooftop sniper's nest that pierced Kirk's neck last Wednesday on the campus of Utah Valley University in Orem, about 40 miles (65 km) south of Salt Lake City.