A teenage boy lured a 12-year-old neighbor girl out of her Utah home by asking for help looking for his lost cat, then strangled her and left her body in a field with a shirt around her neck, prosecutors said.

The 15-year-old boy tried to entice another girl with a similar ruse at another girl's house in suburban Salt Lake City about 20 minutes before he knocked on the door of victim's Kailey Vijil's home, according to the charging documents.

After he was arrested, the teen acknowledged being with her in a field after she left home about midnight Friday, authorities said.

The teen is facing an aggravated murder charge in juvenile court, but prosecutors are asking a judge to allow him to be tried as an adult due to the severity of the allegations, Salt Lake County District Attorney Sim Gill said Tuesday.

The Associated Press is not naming the defendant because he is a juvenile. The AP sought comment on the charges from the teen or his family, but could not verify whether they had a listed telephone number or if the he has an attorney.

The boy has a misdemeanor juvenile record of possession of drug paraphernalia, theft and burglary, with the oldest documented charge dating to last fall, according to court papers released Tuesday. He had been put on probation less than two weeks before Vijil's death, the documents show.

When the teen knocked on the door around midnight Friday, the girl's 14-year-old sister initially answered the door at their West Valley City home but she wouldn't go with him, the charges state. He asked Vijil instead and she agreed, authorities said. Police have said they didn't appear to have had any relationship before that night.

The older sister told their mother, who started looking for the girl when she didn't return. She reported her daughter missing to police at a convenience store about 1:30 a.m. Vijil's body was found less than two hours later.

A juvenile court judge said during a hearing Monday authorities are also investigating possible sexual assault in the case, the Deseret News of Salt Lake City reported. No such charges have been filed, and Gill declined to say whether they could be filed in the future.

The teen is being held in juvenile detention and due to make a court appearance Wednesday.

Gill credited police work in the case for the swift arrest.

The aggravated murder charge typically carries the possibility of the death penalty, but the boy wouldn't face capital punishment due to his age if the case.

The U.S. Supreme Court ruled in 2005 that the death penalty is unconstitutional for anyone who committed a crime while younger than 18.