A 61-year-old man who sexually assaulted a girl for more than six years could be ordered to serve 20 years in prison.

James Robert Wirrell has pleaded guilty in Benton County Superior Court to first-degree rape of a child and two counts of second-degree rape of a child.

Sentencing for the Benton City man is tentatively set for Jan. 12, but that date could be postponed if a state Department of Corrections presentencing report is not completed before then.

According to court documents, the abuse started in 2003 in another state. Wirrell initially inappropriately touched the grade-school girl and groomed her so that it escalated to a sexual relationship when she was a pre-teen, documents said.

The sexual abuse also occurred at various homes and motels in Benton County.

Prosecutors claimed that Wirrell would show pornography on a portable DVD player to the girl, and buy her clothes and presents.

In an interview with detectives, Wirrell admitted to sexually assaulting the victim, along with another teen girl about 22 to 25 years ago, court documents said.

All three of Wirrell's charges include the aggravating circumstance that he used his position of trust with this victim and that the crime was part of an ongoing pattern of sexual abuse.

The aggravating factors will make it an indeterminate sentence, meaning the judge must order a mandatory minimum term but Wirrell's ultimate release date will be decided by the state Indeterminate Sentence Review Board. That will be based on whether he participates in treatment or other programs while in prison.

Deputy Prosecutor Anita Petra said when Wirrell admitted guilt, he did it knowing that she plans to ask for an exceptional sentence of 20 years because of those circumstances.