SALT LAKE CITY — It has been more than four years since her 12-year-old daughter was lured from her doorstep, raped and killed by a teenage neighbor.

Yet for De Shaun Undergust, time without Kailey Vijil remains frozen.

“Even though the years are passing, to me it will always feel like it just happened,” Undergust said Monday, moments before a judge sentenced 19-year-old Jayden Sterzer to up to life in prison.

Kailey would have turned 17 on Thursday, Undergust continued through tears, “but because of what this monster has done to her, she will forever be 12 years old.”

Heartbreak and a gravesite have replaced her daughter’s warm laughter, she added.

As part of an agreement with prosecutors, Sterzer admitted in juvenile court nearly two years ago that he raped the girl. He also pleaded guilty as an adult to a reduced charge of murder, a first-degree felony, and to an additional charge of sexual abuse of a child, a second-degree felony.

Police said a 15-year-old Sterzer went to Kailey’s door late at night on July 17, 2015, and asked her to help him look for a lost pregnant cat, a ruse he had allegedly tried to use with other girls in the neighborhood. Crews discovered her body about three hours later in a horse pasture near her home with scratches on her body and her Batman pajamas strewn around her on the ground.

“This was premeditated and this was heinous,” prosecutor Mikelle Daugherty said.

Friendly and giving, Kailey was quick to donate change to those on the street or a jacket to a classmate who needed one. But she was unable to decipher that Sterzer was a “wolf” at her door that night, Daugherty said.

She noted Sterzer has a criminal history in the juvenile system dating to age 10.

“All the treatment and all the rehabilitation efforts of the juvenile court system could not turn him around,” Daugherty said, adding that Sterzer was on court-ordered house arrest at the time of the girl’s death.

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'Evil came knocking on my door' father says of teen who raped, killed 12-year-old girl

Jayden Sterzer was 15 years old when he asked 12-year-old Kailey Vijil to help find his lost cat, luring her away to rape and murder her. He was sentenced to a secure youth facility Friday, and will eventually be sentenced to prison.

Sterzer’s defense attorney, Michael Sikora, said that by age 9 his client was hoarding food, smearing feces and manipulating others. At age 11, he tried to hang himself.

But it wasn’t until he was criminally charged in Kailey’s death that Sterzer received a diagnosis. In addition to partial fetal alcohol disorder, his client has a number of cognitive impairments and a low IQ, leaving him cognitively at about a third-grade level.

“In this case, it was one child killing another child, and I think it’s important to remember that,” Sikora said. He said his client breaks down in tears sometimes because he knows he’s never going to be normal.

A shackled Sterzer hung his head and issued a brief apology during the Monday hearing, saying that although he cannot fix it now, “I know what I did was wrong.”

He has been held in a secure youth detention facility, where he was expected to remain until age 21, at which point he would be sentenced in the adult system.

But Sikora said it was appropriate to move up the sentencing because his client faces a new criminal charge of assault by a prisoner, a third-degree felony, for allegedly punching a youth center employee and putting him in a chokehold over the summer. A preliminary hearing in that case is set for Thursday.

On Aug. 20, Sterzer was transferred to the Salt Lake County Jail, which due to a communication error released him to his mother on Aug. 26. A warrant was issued and he was rebooked four hours later.

Following the lapse, Salt Lake County Sheriff Rosie Rivera has said Sterzer’s record was sent to the jail over a fax machine that was no longer in use and has emphasized that email and phone calls would be used in the future.

“He should never have been allowed out, even for a second,” and he should not be paroled in the future, either, Undergust said Monday.

Kailey’s father, Orlando Vijil, gripped a podium as he addressed Sterzer, saying others have similar medical issues but “they’re not out there killing anybody.”

“Every time I get a memory of my daughter, it hurts,” he said. “He promised me that he was going to change his life. He couldn’t even do that one year or two years.”

Rupert Steele, Kailey’s uncle and the chairman of the Confederated Tribes of Goshute, said the girl’s death has caused a pain that will last forever, but her killer’s sentencing allows the family to start healing.

“Today as a leader, as I look among my people, she is missing,” he said of his niece.

He submitted a letter to the court alleging the attack was racially motivated — an assertion disputed by Sikora and the judge.

Third District Judge Paul Parker said the killing “has nothing to do with race and prejudice,” but was premeditated and “profoundly wrong.”

“There’s not even a word to adequately describe how bad this is,” Parker said.

He ordered Sterzer to at least 15 years and up to life for the murder charge and a concurrent sentence of least one and up to 15 years for the sexual abuse.

Editor's note: This story has been updated to correct the spelling of Mikelle Daugherty's name.

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