The man operating a boat during a gruesome 2015 accident on Boston Harbor in which a 19-year-old woman lost her right arm pleaded guilty Thursday to criminal charges stemming from the incident.

With the woman looking on in Suffolk Superior Court, Alexander Williams, 26, pleaded guilty to charges of negligent operation of a boat, furnishing alcohol to minors, and tampering with evidence in connection with the accident on May 30, 2015.


Suffolk Superior Court Judge Linda Giles continued the case against Williams, of Boston, without a finding for two years and ordered him to complete 200 hours of community service working with amputees, possibly at Spaulding Rehabilitation Center.

The case will be dismissed if Williams stays out of trouble for two years and complies with all conditions of his release.

“I want him reminded for 200 hours . . . what it means to suffer this type of injury,” Giles said, adding that Williams must also pay $5,000 restitution and enroll in a certified alcohol awareness course.

Giles noted that the woman who lost her arm, Nicole Berthiaume, spoke movingly last week in a victim impact statement about the toll her devastating injuries had taken on her and her family.

“I certainly remember them all,” Giles said of the impact statements from Berthiaume and her parents. “[They] must be the most moving impact statements that I’ve ever heard” on the bench.

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Berthiaume and her family declined to comment Thursday.

Williams said quietly on the witness stand, “I admit to my actions.”

At the time of the incident, Berthiaume was a 19-year-old guest on the Naut Guilty, a boat owned by Benjamin Urbelis, a Boston defense attorney and night club promoter.

Prosecutors allege Williams and Urbelis led a group of 14 people, including a few underage women, for an outing of drinking and socializing on Boston Harbor.

Urbelis is also facing criminal charges and is slated to be tried later this year.

Williams was operating the boat when Berthiaume was swimming in the water, making her way back to the vessel as it drifted near Spectacle Island, prosecutors said.

Urbelis was also in the water at the time, according to authorities.

Williams put the boat in reverse, and Berthiaume was pulled under as she tried to come back aboard. Williams’s attorneys have said he thought she was drowning and was trying to help her.

Prosecutors had charged Williams with evidence tampering after he erased text messages from his phone before handing it over to police investigators.

In her statement last week, Berthiaume recalled waking up the next day in a hospital room with injuries to her abdomen, knees, back, and arms. She was in the hospital for two weeks before she went to a rehabilitation center.

“It wasn’t until then that I realized that although my mind was the same, I was not,” Berthiaume said. “I was a shell of a human being. A shell of who I was.”

She also spoke of the financial toll from her medical bills and the challenges of her disability.

Insurance and a state victims’ fund have paid out roughly $25,000 in medical expenses, and a civil case is also pending.

“You will rarely hear me complain about the incident, and you will almost never hear me complain about my disability,” Berthiaume said last week, according to a transcript of her remarks provided by Suffolk District Attorney Daniel F. Conley’s office. “But that does not mean that it doesn’t kill me every time I look in the mirror, drop something, or accept help from someone.”

Berthiaume had recommended Williams be sentenced to community service and an alcohol awareness course.

“It is important to understand that the mistakes made that day were avoidable,” she said. “Yes, freak accidents happen all the time. But this was not a freak accident. This was an incident created by wrongdoings, an incident created by negligence.”

She also said that the “things that made me me were gone. My penmanship that I took such pride in, going for a drive, swinging a golf club, throwing the football, even taking a shower by myself.”

Prosecutors had recommended a five-year probationary period, as well as a condition that Williams remain alcohol-free during that time and submit to random testing.

Williams’s lawyer, Robert Goldstein, objected to that condition, and Giles sided with him, noting that Williams was not charged with operating under the influence. There is also no evidence that he abuses alcohol, Giles said.

Goldstein said outside the courtroom that his client is “incredibly sorry for what happened that day.”

“It was a tragic accident,” Goldstein said. “Alex’s sole intent that day was to try to help someone he thought was in dire straits.”

Globe Correspondent Dylan McGuinness contributed to this report. Travis Andersen can be reached at Follow him on Twitter @TAGlobe.