A Winchester man received a suspended prison sentence Tuesday after pleading guilty to an allegation that he sexually assaulted a teenage boy at a party in Swanzey around 20 years ago.

As part of a plea agreement, Chester L. Lapointe II, 41, did not plead guilty to a sexual assault charge but rather to one count of second-degree assault related to the incident.

The second-degree assault charge, a felony, states that Lapointe “recklessly” caused serious injury to the victim “by engaging in unprivileged physical contact which resulted in mental anguish and psychological injury.”

According to court documents, the victim said he was between the ages of 15 and 17 when Lapointe — whom he knew through DeMolay, an international organization for young men — molested him at a party in the early 2000s.

Lapointe is a member of Winchester’s budget committee and has previously run for state senator, state representative and the Keene school board.

In court Tuesday, the prosecutor, Assistant Cheshire County Attorney Keith W. Clouatre, said the state’s investigation — including a confidential risk assessment and extensive search of Lapointe’s phone — found no evidence that the behavior was part of a pattern. The possibility of other victims was “the victim’s main concern,” he added.

Clouatre said he did not think it was necessary for public safety to require Lapointe to register as a sex offender at this point, saying it appeared to be an isolated incident.

The victim agreed to the sentence, according to Clouatre.

DeMolay is a youth leadership organization for males between the ages of 12 and 21, according to its website. Lapointe was chairman of the advisory board of the group’s Keene chapter when the allegation surfaced last summer, according to Paul M. Leary, the organization’s executive officer for New Hampshire.

Lapointe self-reported that the victim had posted about the incident on Facebook, and DeMolay in turn notified law enforcement, Swanzey police Lt. Joseph T. DiRusso wrote in an affidavit.

The victim told DiRusso that he and other DeMolay members were at a house in Swanzey and Lapointe, then in his early 20s and an adviser with the group, was providing alcohol, according to the affidavit.

The victim said that he fell asleep, then woke up to Lapointe groping him and initiating other unwanted sexual contact, according to the affidavit. The victim said he told Lapointe to stop and he did, DiRusso wrote.

The victim said he “called the Swanzey Police at the time to report the incident, but did not pursue it further because the officer insinuated that he shouldn’t have been at the party,” DiRusso wrote.

DiRusso wrote that he could not find any record of the incident. Swanzey Police Chief Thomas R. De Angelis did not respond to a request for comment Tuesday.

DiRusso wrote that he spoke to two people who know the victim and said he confided in them years ago that he had been abused.

Leary said Lapointe was suspended from DeMolay as soon as the allegation was reported, per protocol, and Lapointe later submitted his resignation.

“DeMolay International has zero tolerance when it comes to children,” Leary said.

Lapointe appeared remotely at Tuesday’s sentencing hearing in Cheshire County Superior Court.

“He doesn’t recall this incident, but he doesn’t want to cause any pain to [the victim],” his attorney, Richard Guerriero, said. “… He accepts responsibility for his conduct. He’s not contesting what the victim says.”

Lapointe said that while he has no memory of the assault, he takes responsibility and hopes the victim can find closure.

Judge David W. Ruoff accepted the plea agreement, sentencing Lapointe to 1½ to three years in N.H. State Prison, all suspended for five years on condition of good behavior.

Paul Cuno-Booth can be reached at 352-1234, extension 1409, or pbooth@keenesentinel.com. Follow him on Twitter @PCunoBoothKS