LANCASTER — The former Lincoln fire chief will spend the next three years in jail after pleading guilty to half of the 10 charges of aggravated felonious sexual assault against him in a case that involved a developmentally disabled teenage girl.

Nathan Haynes, 67, appeared before Judge Peter H. Bornstein on Monday in Coos County Superior Court and changed his plea to guilty in five of the felony counts against him.

He was sentenced to consecutive 12-month sentences in the Coos County House of Corrections in West Stewartstown on three of the counts, and Bornstein suspended for 10 years a pair of 5-to-10-year sentences on the other two counts.

The sentence structuring allowed Haynes — who had been Lincoln’s fire chief for about 10 years before abruptly quitting that job late last year — to avoid serving his time in state prison, his attorney, John Boyle, said Tuesday. Generally, sentences greater than one year are served in state prison in New Hampshire, rather than in county jail.

In March, a Coos County grand jury indicted Haynes on 10 counts, accused him of sexually assaulting the teenager between June 1 and Aug. 30, 2011, at a camp in Dummer, a small Coos County town north of Berlin.

The indictments stated that Haynes was familiar with the victim and her family, and that he “knew or should have known,” that she had an “intellectual developmental disability.”

In court this week, Haynes answered routine questions from Bornstein, but made no overall statement regarding his actions. Asked Tuesday if his client had any comment to make, Boyle replied, “none whatsoever.”

Haynes will be required to register as a sex offender and must complete sex-offender counseling when he’s released from jail. He’s eligible for time off his sentence for good behavior while incarcerated. Bornstein also placed him on five years’ probation following his sentence, and ordered that he not associate with the victim or her family, and that he stay away from the property in Dummer where the crimes occurred.

Haynes quit his part-time post as fire chief last December, telling town officials he was leaving for “personal reasons.”

But around the same time, Grafton County Sheriff Doug Dutile said Lincoln police asked him to have his department perform a criminal investigation of Haynes. Dutile at the time would say only that the investigation did not involve Haynes’ duties with the fire department.

After the indictments were handed up, the sheriff said the assaults took place at a year-round camp in Dummer, and involved a victim who was not related to Haynes.

bhookway@newstote.com