William Riley Gaul, 19, is accused of firing fatal gunshots into the home of his cheerleader ex-girlfriend

The college football player who fatally shot his cheerleader ex-girlfriend in 2016 returned afterward to his dorm room and fell asleep, his roommate testified Friday at his murder trial.

Prosecutors and the defense agree that William Riley Gaul, now 19, fatally shot Emma Walker, 16, through the wall of her bedroom as she slept inside her Knoxville, Tennessee, home.

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Prosecutors allege the killing was premeditated; his defense argues that Gaul didn’t mean to hit Walker when he fired, but instead made a deadly mistake as part of a twisted plot to present himself as Walker’s rescuer to win her back after she broke up with him.

On Friday, Walker Stanley, Gaul’s roommate and football teammate at Maryville College, testified that after the shooting on Nov. 21, 2016, Gaul showed up at their dorm at 4:45 a.m. and fell asleep, WVLT reports.

“He said he’d been out,” Stanley testified. “That was it. And then he asked if I could help him get up for his 8 a.m. [class].”

After Emma’s body was discovered, Gaul sent Stanley a text on Snapchat asking him not to talk to police, Stanley testified.

Hours before the shooting, Gaul also asked Stanley if he knew how to remove fingerprints from a gun, Stanley testified, according to the Knoxville News Sentinel. Previous testimony alleged that Gaul had put the same question to another friend, Noah Walton, but claimed to be asking on behalf of Stanley.

Image zoom William Riley Gaul, left, and Emma Walker Facebook

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Stanley testified that while he didn’t know Gaul very well, he seemed to be having problems, the newspaper reports.

“I could tell he just wasn’t in a good place in his life,” said Stanley. “He was losing weight.”

Prosecutors charge that Gaul became obsessed with Emma after she broke up with him following a tumultuous on-and-off two-year-relationship, allegedly stalking her in the weeks before he shot her.

Gaul was arrested a day after the fatal shooting. In January 2017 he was indicted on seven criminal counts in the case, including first-degree murder and especially aggravated stalking.

Last week, jurors were shown a secretly-recorded tape of Gaul trying to enlist his friends to help him get rid of the gun used to shoot Walker. On the tape – which was captured by Gaul’s friends at the behest of police – Gaul admits that he stole his grandfather’s gun, but says he didn’t use it to shoot her.

Image zoom William Riley Gaul, left, and Emma Walker Twitter

Defense: Gaul Shot Walker in Botched ‘Coming to Her Rescue’ Plot

During opening statements last Tuesday, Knox County Assistant District Attorney Kevin Allen called Gaul a “premeditated cold-hearted killer,” the Associated Press reports, saying he shot Emma because he was enraged that she had broken up with him permanently.

“On paper, everything looked great,” Allen said, the AP reports. “She’s the cheerleader. He’s the football star. They’re in a relationship. But the relationship was toxic.”

Last Wednesday, Zach Greene, a friend of Emma’s, testified that two days before she was killed, Emma was at a party when she began receiving a string of anonymous texts claiming that someone close to her had been kidnapped. “Go to the car with your keys,” one text stated. “Go alone… I’ve got someone you love. If you don’t comply, I will hurt them.”

When Walker, Greene and a group of friends went outside, they found Gaul face down on the ground, claiming he’d been kidnapped.

Gaul later admitted to sending the texts and making up the kidnapping, according to the prosecutor.

Defense attorney Wesley Stone argued that Gaul never meant to kill Emma, but instead fired at her home because he allegedly wanted to show her he was “coming to her rescue, being her hero,” he said, the AP reports.

As such, he said jurors could consider a charge of reckless homicide but should not convict his client of first-degree murder.