FARMINGTON – A Farmington woman whose SUV struck a snowmobiler last winter pleaded guilty Monday to drunken driving, while her manslaughter charge was dropped because it’s not clear she was solely at fault for the death.

Sarah Forbes, 44, faces up to 10 years in prison when she is sentenced today for aggravated operating under the influence.

On the evening of Feb. 23, she was driving on Routes 2 and 4 in Farmington when her vehicle struck a snowmobile partly in the travel lane. Off-duty Farmington police officer Rick Billian of Strong had gotten off the machine to straighten the snowmobile skis that had gotten stuck on a curb after it crossed the road to a snowmobile trail across from the parking lot of Boivins Harvest House. His fiancee, Lisa Cequeira, 20, of Wilton, was on the machine when it was struck and died of multiple injuries several days later.

The victims’ families will have a chance to testify at the sentencing. They declined comment until after the proceeding.

Forbes was scheduled to go to trial before Justice Joseph Jabar in Franklin County Superior Court on Monday.

Family members and friends of Cequeira, Billian and Forbes waited as state prosecutors and Forbes’ attorney, John Alsop, held meetings and conferred with the judge.

When Forbes and Alsop eventually took seats at the defense table, Billian stared at her for several minutes, leaned his head on his hand, shut his eyes and wiped away tears.

Franklin County Assistant District Attorney James Andrews announced the state would have had problems proving manslaughter beyond a reasonable doubt, and that Forbes’ intoxication level was the significant cause of the accident.

If the case had gone to trial, a state Department of Health and Human Services’ chemist would have testified that Forbes’ alcohol blood content was .23 percent when a sample was taken at a hospital, Andrews said. And a Maine State Police accident reconstructionist would have testified that Forbes’ SUV was traveling between 41 and 47 miles per hour in a 40-mph zone, that the snowmobile was not visible from a distance, and that the grade of the road, a snowbank, the black color of the machine and it being 8 feet into the 12-foot travel lane in the four-lane highway, also were factors in the accident.

The reconstructionist would have testified that that the report concluded it is unclear if alcohol were a factor in the crash, and that even one second of distraction while within 300 feet of the snowmobile would have made an accident inevitable, Andrews said.

Alsop said Forbes never denied being under the influence and takes sufficient responsibility for what happened.

Jabar accepted the plea agreement and said he understood the victims’ concerns, adding these are the most difficult cases with which to deal.

However, evidence related to the cause of the deadly crash could lead to a not-guilty ruling, he said, and Forbes’ plea to a felony charge is not a slap on the wrist.