This is an archived article that was published on sltrib.com in 2016, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

From the beginning, defense attorneys questioned whether a West Valley City teen understood the charges filed against him last year, after being accused of sexually assaulting and killing his 12-year-old neighbor.

And now, almost a year-and-a-half after the now-17-year-old boy was charged with aggravated murder and rape of a child in the July 2015 death of Kailey Vijil, a judge is expected to decide whether the teen is competent to stand trial.

At his first court appearance in July 2015 — a week after Vijil's body was found in a horse pasture — the boy's defense attorney said his client was "confused."

"I don't believe he really understands what's going on here today other than he's been accused of doing something," defense attorney Patrick Corum told the judge.

Since then, the teen has been evaluated by three mental health experts, who all have been tasked to determine whether the teen can understand the court process and appreciate the charges filed against him.

A four-day hearing has been scheduled to begin Tuesday before 3rd District Juvenile Judge James Michie, who will make a ruling about the boy's competency. If the judge rules that the boy is not competent, the case against him cannot proceed.

Michie has closed the hearing to the media and the public, according to Utah court officials.

Prosecutors have said they want the boy to face the charges in adult court. Michie can't rule on that, however, until another hearing is held where the judge will assess the case evidence and consider the severity of the alleged crimes, community safety, the teen's psychological records, family history and rehabilitation needs.

Vijil was found dead at about 1:30 a.m. on July 17, 2015, in an overgrown horse pasture near 3600 South and 5200 West, about a half-mile from her family's home.

Police say the boy lured Vijil from her home just before midnight on July 16, claiming he needed help looking for a lost cat.

Officers found Vijil "lying in the field with a shirt wrapped around her neck," charges state. A medical examiner later determined the girl died from strangulation.

Court documents say a medical examiner also found the girl had been sexually assaulted and that DNA found on her body matched DNA samples from the defendant, who was 16 years old at the time of Vijil's death.

The boy has been held in a juvenile detention facility since then. The Salt Lake Tribune generally does not identify juvenile defendants unless they have been certified to stand trial in adult court.

Twitter: @jm_miller