For a private boarding school that prides itself on being progressive and close-knit, it was a jarring admission.

In a letter mailed to alumni and posted on its website, the Solebury School for the first time acknowledged and apologized for sexual abuse of former students at the hands of faculty from the 1950s to the 1970s.

Administrators said that the claims surfaced only in the last two years, and that they hoped their announcement would help the victims while holding the small Bucks County school to its own standards.

Many in the alumni community were shocked by last month's public apology. And the fallout is just beginning.

Bucks County prosecutors last week said they were investigating sexual-abuse claims at the school across six decades, into the 2000s. Two alleged victims told The Inquirer school officials had ignored their accusations years ago.

A former board member also acknowledged Solebury had chosen to privately handle an abuse allegation that surfaced in the 1990s.

The head of the school declined last week to discuss details of the allegations or name the accused staffers but said Solebury officials had been aware of "less than 10" abuse claims when they issued the apology in late July.

The letter of contrition came despite the fact no claims have been confirmed through civil or criminal investigations or litigation. But Solebury's step illuminates an increasingly common reaction among private schools in recent years to handle allegations with transparency, particularly after Pennsylvania State University's scandal.

"Since [Jerry] Sandusky, I think hundreds, maybe thousands, of former students have approached schools and said, 'Something happened to me,' " said William E. Hannum III, a Massachusetts lawyer who represents private schools. "And I think schools have gotten more comfortable with the idea of being transparent about it - to help victims and not stick their heads in the sand."

Nestled amid the farms of central Bucks County and with tuition costs of between $30,000 and $50,000 a year, Solebury has long been known as an alternative to the rigid, New England-style boarding school experience; a progressive institution, now with 225 students, that has been described as "intimate" and even "iconoclastic."

Teachers take an individual approach with each student, with learning considered a joint venture between them. Claims of sexual abuse involving Solebury last surfaced publicly when David Chadwick, a 25-year-old music teacher, was convicted in 1997 of having sex with a 15-year-old female student.

Jay Abbe, who stepped down from the school's board of trustees last year, said an alumna told board members in 1998 she had been sexually abused at the school decades before. In an interview, Abbe said board members at the time worked to reach a resolution with the woman, "including offers of help as she worked to cope with the situation."

Abbe declined to elaborate or say whether the school had contacted police or alerted other alumni.

Still, Abbe said Solebury's recent letter astounded him and other graduates who still love and support the school.

Monica Furber, chief of Bucks County's special victims division, declined last week to specify a number of alleged victims - or the accused teachers - because the investigation is continuing, she said.

School officials have said two teachers accused by older alumni are dead. And the statute of limitations for criminal or civil action may have expired for older cases.

The school's apology has prompted one woman to reach out to police. In a statement that her lawyer, Jeff Fritz, shared with The Inquirer, the alumna claims she was sexually abused by a Solebury teacher in the 2000s, long past the era of misconduct identified by the school and possibly still within the criminal statute of limitations.

The woman said Solebury administrators were aware of the "inappropriate contact" at the time but "did not contact police, as they should have."

She also criticized the school for encouraging victims to contact the law firm it hired as well as the District Attorney's Office.

"I am enraged and feel victimized for a second time with the way the school has chosen to handle this years ago as well as presently," the woman wrote. "Instead of reporting the abuse of power to police originally, they are now attempting to resurrect the past as if they are supporting the victims/alumni when really they are simply trying to still just protect themselves."

Another alumna from the 1970s said last week a male teacher in his mid-20s had sex with her when she was 14. "I was not raped - but it shouldn't have happened," the woman said.

Now in her 50s, she said she did not share the information with school officials until the early 2000s. She said they never called back.

"I would like for the truth to come out," she said. "But I'm still really suspicious of the reason why they've come out with this now."

Tom Wilschutz, head of Solebury since 2008, said the public letter was a reaction to a handful of older alumni - "less than 10" - who approached the school in the last two years. They alleged abuse by teachers in the 1950s, '60s, and '70s.

"I know we unleashed a process when we sent that letter," Wilschutz said in an interview. But he said the school's goal was to help victims while living up to its values, including transparency. "When we were given this information, we took action," he said. "We believed the allegations. And we believe, as great a school as Solebury is, we have to live up to our past."

Solebury has hired the Philadelphia law firm Pepper Hamilton to help investigate the claims. That is the same firm hired by the Carolina Friends School in Durham, N.C., which in June published a similarly worded letter about a former principal and a former teacher who students said sexually abused them from 1969 to 1975.

In Solebury's letter of apology, top officials wrote: "[the] close and collaborative relationship between teacher and student is an important part of our approach to education. However, we will not permit that ideal to be used as a proxy or a justification for an inappropriate sexual relationship between an adult and a student at Solebury School. Not in the past. Not now. Not in the future."

Many alumni reached by The Inquirer spoke highly of their school.

"Academically, it was strict; you had to really work," said Jane Craven, who graduated in 1966. "And yet they always were looking to the individual for your strengths. And if you had weaknesses, they talked to you about it. It was very individualized."

Craven said she was unaware of any misconduct between students and teachers, although she said her roommate married her English teacher after graduation.

"Everybody was sort of surprised about that," Craven said. "But we were watched over very carefully. I think it's one of the finest experiences I've had in my life."

Some alumni from the 1970s describe a time of relaxed rules and oversight, when students - many sent to boarding school after a divorce - smoked marijuana and had sex.

A 1976 graduate, Brad Acopulos, said there were moments when crossing the line between students and teachers appeared to have zero consequences, but they weren't the norm.

"I can't say I ever saw a teacher go after any students," he said. "I'm just saying there was enough of a culture that I could see consensual sex happening."

Another 1976 graduate, Jill Lenzer, said one teacher had been rumored to be having sex with students. But she said she and her female friends spent hours with him without a single "inappropriate touch."

"Solebury was actually a refuge for many of us," Lenzer said. "There were a number of kids who didn't have great family support networks and who grew up in boarding schools. Solebury became a family to them."

Rusty Cassway, who graduated in 1983, said getting the school's letter was like "an old friend let me down." He said he was unaware of any abuse. Teachers treated students like adults, which made them want to learn, he said.

"I could see how stuff could happen because of the closeness between students and teachers," he said. "But it would have never occurred to me."