Charlie Kirk, a prominent political ally of former President Donald Trump, was fatally shot on September 10 during an outdoor event with students at Utah Valley University in Orem, Utah.

On Tuesday, Utah County Prosecutor Jeff Gray announced that he will seek the death penalty against 22-year-old Tyler Robinson, revealing messages in which Robinson allegedly admitted to his involvement to his live-in partner. Authorities said the partner, a biological male currently undergoing gender transition, turned over the messages to law enforcement.

According to the transcripts, Robinson described retrieving and handling the rifle used in the shooting and admitted to planning the act for over a week. He also expressed remorse for involving his partner.

Prosecutor Gray confirmed that Robinson left DNA on the rifle trigger and faces aggravated murder charges, which could carry the death penalty if convicted. “The murder of Charlie Kirk is an American tragedy,” Gray said.

Robinson allegedly shot Kirk in the neck from a rooftop near the university campus. The shocking case has drawn national attention due to Kirk’s political prominence and ties to conservative movements.