Charlie Kirk shooting suspect's conditions for surrender had to be 'gentle': Sheriff

Tyler Robinson, the suspect who was charged in the shooting of Charlie Kirk , was apprehended in what needed to be "gentle" conditions when he turned himself in to authorities, according to the Washington County Sheriff's Office.

At 8:02 p.m. on Sept. 11, Washington County Sheriff Nate Brooksby said he received a call from a retired detective, with Brooksby saying he "couldn't fathom" what would come "out of his mouth."

He told Brooksby, "I know who Charlie Kirk's shooter is," the sheriff said during a press conference on Wednesday.

Just before 10 p.m. that night, Robinson, his father and a close friend who previously worked in law enforcement drove together from Washington, Utah, to the Washington County Sheriff's Office in Hurricane, Sgt. Lance Alfred, a spokesperson for the sheriff's office, told ABC News.

During the drive, the family friend called the personal cellphone of the Washington County Sheriff's Office patrol division chief to report the suspect was about to turn himself in, Alfred told ABC News.

Robinson, the 22-year-old who was charged with aggravated murder on Tuesday, allegedly "knew it was inevitable that he would be caught" and was "fearful of being shot by law enforcement," Washington County Sheriff officials said during a press conference on Wednesday.

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When Robinson arrived at the sheriff's office, he was taken into a building marked "Authorized Personnel Only," with personnel from the sheriff's office notifying the Salt Lake City FBI office and other local law enforcement officials of the suspect's arrival, Alfred told ABC News.

Robinson was kept in the back offices of the sheriff's office and turned over to the FBI and other law enforcement upon their arrival, which was just before 6 a.m. on Friday.

He was described as "quiet and somber," officials said on Wednesday. Officials said they attempted to make conditions "gentle" and "inviting" for Robinson before the FBI and other law enforcement arrived.

Robinson was formally charged with aggravated murder on Tuesday, with prosecutors announcing the intent to seek the death penalty. He was also charged with felony discharge of a firearm causing serious bodily injury, obstruction of justice, two counts of witness tampering and commission of a violent offense in the presence of a child, Utah County Attorney Jeff Gray announced.

The suspect also made a short first court appearance on Tuesday.

Prosecutors on Tuesday offered more insight into the killing and Robinson's alleged discussions with family and his roommate in the wake of the shooting.

After his father recognized Robinson in photographs released by authorities, the suspect met with his parents and "implied that he was the shooter and stated that he couldn't go to jail and just wanted to end it," the charging documents said.

His parents then asked their son why he committed this crime, to which he said "there is too much evil and the guy [ Charlie Kirk ] spreads too much hate," according to the charging documents.

RELATED: Tyler Robinson said he killed Charlie Kirk because he 'spreads too much hate': Officials

Exactly what Robinson was allegedly referring to by "hate" was not clear. Investigators noted that Robinson's mom told them that her son allegedly began having a relationship with his roommate, who is transitioning, and had begun leaning to the left more politically, becoming "more pro-gay and trans-rights oriented," but the document does not indicate the relevance of those stances nor whether Kirk's remarks about those issues were a motivating factor.

Gray said he would let a judge determine whether the statements allegedly made by Robinson constituted a confession. On Tuesday, he declined to comment on whether Robinson has been cooperating or spoken to investigators.

Prosecutors also revealed text messages between the suspect and his roommate.

On the day of the shooting, the roommate received a text message from the 22-year-old that said, "drop what you are doing, look under my keyboard," charging documents said.

The roommate found a note underneath Robinson's keyboard that said, "I had the opportunity to take out Charlie Kirk and I'm going to take it," according to charging documents.

Prosecutors also revealed additional conversations between the suspect and his roommate after the shooting.

"I had enough of his hatred. Some hate can't be negotiated out," one of the messages read.

Robinson's roommate asked how long he had been planning this attack, to which he said "a little over a week I believe," according to charging documents.

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As the suspect remains in custody without bail, FBI Director Kash Patel said a "number of individuals" are currently being investigated who are linked to the suspect's Discord, a group chat messaging platform where Robinson allegedly confessed he was the shooter two hours before he was taken into custody.

"Hey guys, I have bad news for you all...It was me at UVU yesterday. im sorry for all of this," one of the messages read.

During a Senate Judiciary Committee hearing on Tuesday, Patel said "a lot more" than 20 people are linked to Robinson and that the FBI is looking into "anyone and everyone involved in the Discord chat."

Robinson's next hearing is scheduled for Sept. 29.

ABC News' Jaclyn Lee contributed to this report.