A teenage girl has agreed to testify against more than a dozen males accused of sexually assaulting an 11-year-old girl, a prosecutor said Friday.

The 16-year-old girl, who was accused of coaching the younger girl, is charged with being party to four counts of first-degree sexual assault of a child.

Under a plea deal, she will be prosecuted as a juvenile instead of in adult court as part of the plea deal, said Matt Torbenson, an assistant district attorney.

"I believe her testimony will prove to be key against many of the adult offenders," Torbenson told Children's Court Judge Thomas Cooper.

According to court documents, the 16-year-old girl encouraged the younger girl to perform oral sex on the males in the house on Labor Day. An adult woman was present but did nothing to stop it, according to records.

Torbenson said the 16-year-old girl is remorseful, has no prior record and has helped identify those who took part in the assault.

She is cognitively disabled and also has a drug and alcohol problem, according to a psychological report filed in court Friday.

He said that as part of the plea deal, prosecutors also would recommend she get three years in a juvenile detention facility and two years of supervision.

If convicted in adult court, she could have faced up to 60 years in prison on each count.

A 14-year-old boy was sentenced to one year in juvenile detention on Tuesday after pleading guilty to being party to the first-degree sexual assault of a child in the case.

He was the first of 14 people charged in the case — seven of them juveniles — to be sentenced.