SALT LAKE CITY — A Utah man pleaded guilty Wednesday in the brutal killing of a 15-year-old girl, admitting he murdered her to prevent her from reporting him to police after she broke up with him.

West High School student Baleigh Bagshaw was on the phone with her mother when she returned from school on May 7, 2018, and found Shaun Patrick French at her family’s house. French admitted waiting alone for her inside, where he stabbed her several times and slit her throat.

French, 26, entered the guilty plea in Salt Lake City’s 3rd District Court to aggravated murder, a first-degree felony, as part of a plea bargain with prosecutors. In exchange, the Salt Lake County District Attorney’s Office agreed not to seek the death penalty and several remaining charges against French were dismissed.

The plea deal stipulates French will spend life in prison without the possibility of parole. Prosecutor Richard Pehrson said Baleigh’s family approved of the agreement.

Baleigh Bagshaw, 15, was killed inside her house while on the phone with her mother. | Facebook

In a statement of facts supporting the guilty plea, defense attorney Michael Misner said his client knowingly caused Baleigh’s death without justification and to prevent her from testifying or to prevent evidence from being used.

Misner said his client initiated a sexual relationship with Baleigh while living in her home — when he was 23 and she was 14 — even though he knew it was illegal because of her age. The relationship continued on and off for over a year until the girl broke up with him in March and began dating others her own age, Misner said.

Baleigh rejected French when he tried to persuade her they should get back together, and her family informed French he was no longer welcome at their home, Misner added.

“Defendant still refused to accept the breakup,” Misner said, and tried to force Baleigh to get back together by threatening violence to the girl, her family and himself.

He told her over Facebook that “I’m dead and that mean(s) your family will be too including future things like husband or kids,” saying their deaths “will be on your hands.” When she did not respond, French wrote that he was “done” and “I want you to suffer so enjoy,” court documents say.

The girl made a plan with her mother to report him to police but first informed French. He was in Ohio at the time and drove back to Utah to kill her and prevent her from going to police, Misner said.

French broke into the home while her mother was at work and attacked Baleigh, nearly decapitating her, Misner said. When he left the house, he tracked blood out the door, discarding the knife in her backyard and dumping his bloodied clothes in a Wyoming landfill.

French was arrested in southeast Colorado following a two-day manhunt.

Man 'obsessed' with West High teen charged with murdering her
Slain West High student remembered as 'sweet' and friendly
State seeks death penalty for Utahn accused of killing teen girl

Shawna Bagshaw has said her daughter loved her two pet dogs and dreamed of someday training others for therapy or to help with search-and-rescue efforts.

Four years before her death, Baleigh’s father died of liver failure. The girl had inherited his love of bands like AC/DC, Kiss and Nirvana. She also was excited to become an aunt to a baby niece, Bagshaw said.

On Wednesday, a shackled French wore a yellow jail uniform and glasses, replying “guilty, your honor,” when the judge asked for his plea.

A short time earlier, French said he had reviewed a plea form with his defense attorney but there were some things he didn’t agree with. He said he wanted to go forward nevertheless.

“Your honor, to be honest, it’s either this or the death penalty,” he said.

At the urging of Judge Paul Parker, French and his lawyer left the courtroom to review the paperwork. They crossed out one sentence with details about the murder.

In the courtroom, French asked how a jury in a death penalty case could ever be impartial if the jurors must be open to approving capital punishment for a defendant. The judge said those jurors must be committed to weighing facts and evidence and not to a certain outcome.

French paused again to talk with Misner about the possible sentence he would face if he were to go on trial, compared to the plea agreement.

“This is the only thing to do,” he said when the judge asked if the guilty plea was in his best interest. “Yeah. It’s either this or die.”

The charges dropped as part of the plea bargain are: aggravated burglary, a first-degree felony; obstructing justice and sexual exploitation of a minor, second-degree felonies; and two additional charges of witness tampering, also a second-degree felony.

Sentencing is Aug. 25.