The suspect wasn’t even sure what model of gun he’d used, according to messages with his roommate.

“I don’t fully know what the gun was, because it was old… and Gramps did some modifying,” he wrote.

Twiggs testified that Robinson had asked weeks earlier about using an engraving tool in advance of an upcoming hunting and camping trip with his family.

After the shooting, however, he texted Twiggs: “Remember how I was engraving bullets?”

He said the messages were “mostly a big meme”.

The court saw pictures this week of inscribed bullets and cartridges found both at the crime scene and Robinson’s residence – with messages such as “Hey Fascist! Catch!”

Robinson eventually gave up trying to retrieve the rifle, he texted Twiggs, and made his way back to their home in St George.

Authorities did discover the firearm, law enforcement testified this week, and found DNA matching Robinson on both the rifle and a towel it was wrapped in.

Robinson, meanwhile, was nervous and regretful in the apartment he shared with his roommate the day after the shooting, Twiggs said in the recorded interview.

“He started crying a little bit and said he wishes he hadn’t done it and then kept going around and just doing stuff, I think to keep himself busy or distracted or something,” Twiggs said.

The hearing featured lengthy debates over the admissibility of evidence – with media lawyers and Kirk representatives arguing passionately for everything to be displayed publicly or at least in the courtroom.

Robinson told his roommate the day after the killing that he intended to turn himself in, Twiggs said.

The court heard how the suspect arrived at Washington County Sheriff’s Office the day after the shooting, accompanied by his parents and a family friend.

Prosecutors played soundless footage of him that night, wearing a maroon shirt, dark hat, jeans and Converse shoes, and he was transported back to Utah County and formally booked on 12 September.

This week, Robinson appeared in court clean-shaven and wearing light-coloured suits. His parents and two brothers were also there.

The US president’s son, Donald Trump Jr, and his wife were in court, too.

Both sides must now submit lengthy written briefs, and Judge Graf set the next hearing date for 1 September.

The Kirk family released a statement shortly after court adjourned.

The family wrote: “Nothing will ever undo the loss of our beloved Charlie.

“As this case moves into its next phase, we pray that truth will continue to be heard through a process that is fair, transparent, and grounded in the facts.”