A rape trial that drew intense scrutiny to one of New England's elite boarding schools has cast a shadow over other prestigious prep schools as they start a new year.

Somber letters going home to parents at some schools outline their plans to tackle issues related to sexual violence, drawing on events at St. Paul's School, an exclusive Concord, New Hampshire, boarding school that spent the summer embroiled in a high-profile rape trial.

Owen Labrie, a former St. Paul's senior from Tunbridge, Vermont, was cleared of charges he raped a 15-year-old girl, a freshman, but was convicted of lesser charges. He denied having intercourse with the girl; she said the 18-year-old Labrie was aggressive and she told him, "No, no, no."

The trial revealed a school tradition called Senior Salute, in which seniors competed to have sex with underclassmen. News of that tradition drew heavy criticism to the school and sent waves through other top-tier boarding schools.

Leaders at Phillips Academy Andover in Massachusetts, in a letter to parents, said they were "heartbroken for those affected by this sad and upsetting matter."

"For high schools everywhere, this trial raised hard and important questions about sexual assault, adolescent decision-making, and institutional procedures and policies," Andover's head of school, John Palfrey, wrote last week.

A similar letter sent to parents at Phillips Exeter Academy in New Hampshire said the school's leaders "grieve for the pain we know so many feel."

Both letters detailed new and continuing efforts to combat sexual assault. The schools said they were planning the updates before the trial.

Andover updated its rulebook with a section on sexual consent and adopted an affirmative-consent policy like those sweeping across colleges in some states. The policy says that, for students legally old enough to have sex, partners must give consent as "a clear, verbal 'yes.'"

The school also is narrowing the window when students can visit each other's bedrooms, and it now requires students to keep doors open and lights on during all visits, except for seniors nearing graduation.

At Exeter, officials plan a new bystander intervention program, which will train students to help prevent sexual violence.

St. Paul's has said it's committed to teaching its students to act honorably. More than 20 other boarding schools that were contacted declined to comment or didn't return calls.

The case at St. Paul's, whose alumni include U.S. Secretary of State John Kerry and former FBI Director Robert Mueller, adds to the list of scandals that have shaken New England's prep schools.

Milton Academy, near Boston, expelled five male hockey players in 2005 after they received oral sex from a sophomore girl. Deerfield Academy, about 2 hours west, found in 2013 that a teacher had sexually abused students in the 1980s.

An association that represents boarding schools, though, said their problems are no worse than those at other schools.

"These are issues that unfortunately our society is dealing with, and teenagers are dealing with," said Peter Upham, executive director of the Association of Boarding Schools, based in Asheville, North Carolina.

He said schools do a lot to address these issues but prep schools seem to attract lopsided attention because "there's a certain intrigue that these schools represent."

Some experts, though, contend the freedom given to students at boarding schools, coupled with traditions dating to when the schools admitted boys only, makes them vulnerable for sexual assaults.

"There's enormous pride in these institutions and their histories, and I think there's a deep reluctance to change tradition," said Karen Gross, a past president of Southern Vermont College and a former senior policy adviser to the U.S. Department of Education.

Others noted that boarding schools offer the space to escape adult supervision. Cindy Pierce, who speaks about sexuality at prep schools, said she routinely hears about students sneaking to the privacy of theaters or attics to have sex.

Exeter senior Thomas Chou said his school has a "prevalent hook-up culture" fueled by the independence given to students.

"Our parents aren't with us," he said. "We're living in dorms."

Upham, of the school association, said he believes boarding schools provide "appropriate" supervision. Still, he added, "There's always room for improvement."