BOSTON — A new lawsuit has accused St. Paul’s School, an elite boarding school in Concord, N.H., of a decades-long “pattern of negligence” related to sexual misconduct and accused a former teacher who had not previously been publicly named in connection with the abuse.

The suit, filed on behalf of two alumni of St. Paul’s and one of their wives, accused Gerry E. Studds, a former United States representative from Massachusetts who had taught at the school, of inappropriate conduct. Mr. Studds died in 2006. His family members could not be reached on Thursday for comment.

“St. Paul’s was a haven for sexual predators, and the school was negligent in failing to prevent the sexual abuse of its students,” said the lawsuit, which was filed this week in Merrimack County Superior Court New Hampshire. It also accused four other educators of sexual misconduct, all of whom have previously been named in investigations released by the school.

The lawsuit marks a new round of allegations against a boarding school that has been mired in reports of years-old abuses and questions about its handling of more recent allegations of sexual misconduct by students. Last year, investigators hired by the school named 13 former faculty and staff against whom “substantiated” claims of sexual abuse and misconduct have been made; the investigators added more names in a follow-up report. The school is the subject of an investigation by the New Hampshire’s attorney general.