The morning Seth Fontenot killed 15-year-old Austin Rivault, he pulled the trigger of his 9 mm Beretta while wearing only underwear and red Converse sneakers.

Fontenot was tired of being a victim, fed up with having his truck and his mom’s car broken into at their Lafayette home. He suspected the noise that awoke him at 1:45 a.m. that Sunday was kids once again breaking into his vehicle.

Fontenot wanted Rivault and two other teens, whose identities he didn’t know at the time, to respect the authority he wielded while holding his gun.

“I shot … and then I shot … and then I shot. It wasn’t bam bam bam,” Fontenot told Lafayette police Detective Larry Theriot later that morning of Feb. 10, 2013.

Fontenot, who was 18 at the time, described to Theriot the methodical, deliberate way he shot at the truck as it sped away from him, down Green Meadow Road and out of sight. Fontenot said he fired the three shots in 1½- to 2-second intervals.

Inside the truck, Rivault lay in the back seat, dying or already dead from the bullet that struck him in the head. The driver, Cole Kelly, a bullet in his bleeding leg, was trying to get to Johnston Street and to a hospital. Front seat passenger Will Bellamy was shot, too, and bleeding. Kelly and Bellamy survived.

Details about the morning Rivault died are contained in transcribed interviews Theriot and other detectives had with Fontenot and Kelly. The documents are part of Fontenot’s voluminous court file. Fontenot, now 20, is scheduled to stand trial Dec. 1 on one count of first-degree murder in Rivault’s death and two counts of attempted first-degree murder for shooting Kelly and Bellamy.

All three victims were 15 at the time and freshmen at Catholic high schools in Lafayette — Rivault and Bellamy at St. Thomas More, Kelly at Teurlings.

The transcriptions were filed into the court record in September by Fontenot’s attorney, Thomas Guilbeau, along with a motion seeking more details from prosecutors.

The documents containing the transcriptions are the rare exception in the case. Inexplicably, they were not sealed from public view as are almost all other 2014 court filings in the case containing details of what happened on the fateful night of the shooting.

Also sealed are courtroom hearings for Fontenot. Judge Ed Rubin in a September hearing cleared the court of media and all other nonfamily members before proceeding.

On Monday, Rubin will hold another closed-door hearing, the final hearing before Fontenot’s trial starts Dec. 1. Fontenot, a former University of Louisiana at Lafayette accounting major, faces life in prison. Prosecutors are not seeking the death penalty.

The unsealed document also contains a transcribed interview Theriot and other detectives held with Kelly on Feb. 11, 2013, after he was released from medical care.

Kelly said he was taking Rivault home from an after-party that followed a Mardi Gras parade. The party was in or near the Bellevue Plantation neighborhood where Fontenot and Rivault lived. Kelly told Theriot he was driving because he didn’t want Bellamy, who had been drinking alcohol, to drive.

“They went and steal some alcohol,” Kelly said, “… but they weren’t being cocky about it.”

Kelly told detectives Bellamy had gotten drunk and that Rivault might have been drinking alcohol, too. Kelly said he had not been drinking alcohol.

Rivault, sitting in the back seat, was giving him directions to his home when, all of a sudden, “I remember seeing the white body (Fontenot in underwear and sneakers) just pop up and … I heard the loud pow” of a gun.

Throughout the interview, Theriot asked Kelly if anyone got out of the truck between the time they left the party and when they arrived at Our Lady of Lourdes Regional Medical Center seeking help. Theriot told Kelly that Fontenot and others in Bellevue Plantation subdivision who were awake that morning reported seeing boys sneaking around carports.

Kelly repeatedly said no one got out of the truck until they arrived at the hospital.

Less than eight hours after the shooting, police picked up Fontenot from his River Ranch restaurant job. Theriot and other detectives interviewed Fontenot, who answered freely and never asked for an attorney.

Fontenot told detectives that he was sleeping in his room with his girlfriend when he heard what sounded like someone popping the lock on a vehicle. He’d heard that sound before.

Looking outside, he saw a truck that looked like the same Chevrolet that, in early December 2012, carried thieves who broke into his mom’s vehicle.

Outside his home, nearly naked and holding his pistol with the trigger safety switch on, Fontenot yelled, “Stop! Freeze, freeze! Stop!” according to the transcript. “… I don’t remember what went through my head … from whenever I turned … my safety off. … I don’t remember squat.”

Fontenot said he did remember shooting three times in the controlled manner he was taught. He said he aimed at the tailgate or the lights. He said he wanted the boys to realize that their crime of breaking into vehicles had victims.

“Did you have intentions of hurting these children?” Theriot asked.

Fontenot at first answers with a disjointed sentence about it being his property that was being damaged. “I just wanted to show ’em like, you know, this is what you’re doing to me.”

Then Fontenot said, “And now I just, I can’t believe I done this. … I can believe I shot that, that truck, but I just can’t … I shot someone.”

A few minutes into the interview, Fontenot learned he killed a boy who lived just four doors down from him on Green Meadow Road. Twice during the interview, Fontenot stopped and cried.

“And when you pulled that trigger, did it cross your mind, ‘I might hit somebody or hit a neighbor or hit something?’ ” Theriot asked.

“No, I didn’t,” Fontenot said. “(I’m) severely sorry.” Fontenot said Rivault might have grown up to be “somebody great.”