PROVO, Utah (AP) — During the frantic search to find Charlie Kirk’s assassin, the 22-year-old man now charged with capital murder texted his romantic partner and confessed to carrying out an attack he planned for more than a week, court documents said.

Prosecutors revealed a series of incriminating texts, a hidden note and DNA evidence while announcing the charges and their intent to seek the death penalty against Tyler Robinson in the killing of Kirk, a prominent conservative activist and confidant of President Donald Trump.

Investigators say that sometime after Robinson fired a single fatal shot from the rooftop of a Utah Valley University building overlooking where Kirk was speaking to about 3,000 people on Sept. 10, he texted his partner and said to look under a keyboard.

There was a note, “I had the opportunity to take out Charlie Kirk and I’m going to take it,” according to court documents.

After expressing shock, his partner who lived with Robinson in southwestern Utah, asked Robinson if he was the shooter. Robinson responded, “I am, I’m sorry.”

Utah County Attorney Jeff Gray said that DNA on the trigger of the rifle bolt-action rifle used to kill Kirk on the campus in Orem, south of Salt Lake City, matched Robinson. That rifle had been a gift from Robinson’s grandfather, the prosecutor said.

Robinson appeared briefly Tuesday before a judge by video from jail. He mostly stared ahead as the judge read the charges and said he would appoint an attorney to represent him. Robinson’s family has declined to comment to The Associated Press since his arrest.