AUBURN — A former Bethel police officer will spend 21 months of an eight-year sentence behind bars for sexually assaulting a woman in 2017.

Shayne White, 52, of Poland appeared Wednesday in Androscoggin County Superior Court, where the judge who presided over the September jury trial imposed White’s sentence.

White will be on probation for two years after his release from prison. He must complete an evaluation, counseling and treatment as a sex offender and continue substance abuse treatment. He will be required to register as a sex offender for life and be barred from having any contact with the victim.

Shayne White, a former Bethel police officer, was sentenced Wednesday in Androscoggin County Superior Court for a gross sexual assault committed in 2017.

The sentence was a compromise, Assistant District Attorney Alexandra Winter said, citing a “rather unusual circumstance.”

“This is a rather lenient sentence,” Winter said. “It’s certainly less than what I would have recommended at the sentencing hearing, but to spare the victim from having to go through a possible retrial on this issue, we are satisfied with the sentence.”

Defense attorney Sarah Glynn had sought a mistrial during jury selection when a member of the jury pool who was being questioned made negative comments about a lawyer involved in the case. In January, Glynn filed a motion for a new trial.

Justice Robert Clifford denied both of Glynn’s motions, but agreed Wednesday a compromise sentence would spare the victim from having to endure a second trial.

He said White has a “fairly substantial issue on appeal that could well result in vacating of the conviction.”

In exchange for the more-lenient sentence, White agreed not to pursue an appeal.

Winter said the victim approved of the compromise sentence.

“It’s a good result,” Clifford said.

A charge of gross sexual assault is punishable by up to 30 years in prison.

In a statement to authorities. the victim had written that White had entered her home while she was sleeping and forced himself on her. She said she had been invited into White’s home earlier in the evening for a drink.

White was arrested June 10, 2017.

He had served as a lieutenant with the Bethel Police Department from 2004 to 2008, then as chief. The department was disbanded in 2010 when residents voted to do away with it and contract with the Oxford County Sheriff’s Office. White later worked as a security officer, according to court documents.