A Vineyard Haven man and former Edgartown supermarket manager was sentenced in Dukes County Superior Court on Wednesday to 10 years in jail for the rape of another former store employee early this year.

Peter Duart, 42, also was convicted of indecent assault and battery of the ailing, 69-year-old victim, who is a resident of Oak Bluffs, and sentenced to three years of probation to begin at the conclusion of his jail time.

Originally the second charge was assault and battery of a retarded person, but this was changed after the Hon. Cornelius Moriarty 2nd, an associate justice of the superior court, found doubt about the extent of the victim’s mental impairment.

In passing his judgment against Mr. Duart, Judge Moriarty said Mr. Duart had preyed on a vulnerable victim who was mentally and physically inferior to him and who saw Mr. Duart, his former manager, as an authority figure.

It was the second time Mr. Duart had been convicted of similar charges in similar circumstances. In a 2003 case, he also was found guilty of rape and assault and battery of a retarded person, and the victim was then also a person who worked at the supermarket. For that crime he was sentenced to two years in prison followed by three years of probation.

Cape and Islands assistant district attorney Jennifer Bright referred to Mr. Duart’s history of “targeting” vulnerable people, as she sought an 18 to 20-year sentence on the rape and 10 years-plus probation on the assault charge.

J. Drew Segadelli, counsel for Mr. Duart, had sought four to five years for his client.

The case was unusual in that Mr. Duart elected not to be tried by a jury, but by judge alone, and the victim’s evidence was given by video deposition taken in July. He is suffering from late stage cancer.

The case rested largely on that evidence, and on telephone records showing Mr. Duart called the victim several times in the early hours of Jan. 30.

The victim worked for 49 years packing groceries and moving shopping carts at the Edgartown supermarket, formerly the A& P, now the Stop and Shop. Mr. Duart was one of his managers at the A& P.

The victim testified that he received a telephone call early in the morning hours, and recognized the caller’s voice as that of Mr. Duart.

Mr. Duart also identified himself as his manager at A& P, the victim said, and demanded to come over to his place.

“He wanted to get together,” the victim said.

Mr. Duart subsequently turned up in a taxi about 3:30 a.m. and the victim let him in. They sat on the couch in the living room, and Mr. Duart “started grabbing” his private parts and performed oral sex on him, despite the fact that he said no.

The victim’s evidence was somewhat inconsistent as to the degree of resistance he offered. At one point he said he was too scared to do anything except sit with his hands at his side; at another point he said he tried to push Mr. Duart away, but he was too strong; at another point he said Mr. Duart picked him up and threw him on the couch.

After the incident, the victim drove Mr. Duart home.

Subsequently, he said in evidence, he told a person who helped clean his apartment what had happened.

That person, Robert Carey of West Tisbury, a nursing assistant with the Vineyard Nursing Association, contacted police.

Following an investigation, Det. Nick Curelli of the Oak Bluffs police sought a warrant for Mr. Duart’s arrest on March 17.

Other than verbal, the only evidence offered at trial were telephone records which showed three calls from Mr. Duart’s number to the victim’s telephone.

The question of the victim’s intellectual capacity took up most of the second day of the trial on Wednesday.

Dr. Louis Roy, a forensic psychologist, testified that he had administered IQ tests which showed a mild to moderate intellectual disability. He also noted in his report that at the time of the testing, the victim was bedridden with cancer and was lethargic, sedated and slow to react to questioning.

Mr. Segadelli drew his attention to suggestions the cancer may have metastasized to the victim’s brain. Dr. Roy said he was aware of that. Mr. Segadelli also challenged Dr. Roy about the victim’s demonstrated competence: he had held a driver’s license for more than 40 years and had driven without incident all that time, had lived largely independently, had paid his own bills, and had held paid employment.

Dr. Roy said none of that was necessarily inconsistent with intellectual disability.

In closing, Mr. Segadelli said the court had to consider whether there could have been some form of consent in the incident between the victim and Mr. Duart. There was, he said, “not one thing” to corroborate the story as told by the victim. No cab record, no analysis of the computer items, no physical evidence.

The probability was that “something happened” on the night in question, but rape and assault and battery had not been proven beyond reasonable doubt, the defense attorney said.

Judge Moriarty conceded it was “not an easy case to decide.”

But he said he had “no trouble” concluding that the victim was a truthful witness and “no doubt” there was a sexual encounter that night. There was no motive for the victim to fabricate his evidence, the judge said, and telephone records were consistent with the victim’s version of events.

As to whether the sexual encounter was accompanied by force, Judge Moriarty distinguished between two kinds of force, physical and constructive, and said he was convinced Mr. Duart had used constructive force through his greater physical and mental powers and his perceived authority.

However, while he thought the commonwealth had made the case that the victim was of below-average mental ability, it had not proven to his satisfaction that he was mentally retarded under the law.

He reduced the charge to assault and battery.

Mr. Duart will serve his 10 years at the Massachusetts Correctional Institution at Cedar Junction (formerly Walpole) on the rape charge. And he was ordered to provide a DNA sample to be held on the state database.

On the second charge, Mr. Duart was placed on three years probation, which will begin after he finishes serving time in state prison. Conditions of the probation will include a midnight to 6 a.m. curfew, GPS monitoring and a prohibition on the supply of alcohol or drugs or possession of pornography. He will be required to live in an approved residence after release, and apply to the court before taking a job or volunteer position.

Mr. Segadelli said the case would be appealed.