An elite New Hampshire boarding school alerted alumni this week that a longtime teacher has admitted to two cases of sexual misconduct with students in the 1970s and 1980s.

Phillips Exeter Academy sent an email to alumni Wednesday that Rick Schubart, who taught history at the school for 38 years, acknowledged the misconduct in both cases, which were reported in 2011 and 2015. He was forced to retire and leave campus housing in 2011. It was not until the 2015 report that he was stripped of his emeritus status and banned from campus, said the letter signed by Principal Lisa MacFarlane and Board of Trustees President Eunice “Nicie” Johnson Panetta.

At least one of the reports was made under the tenure of principal Thomas Hassan, husband of New Hampshire’s Democratic Gov. Maggie Hassan, who is currently running for U.S. Senate.

The revelations make Exeter just the latest elite prep school to grapple with allegations of sexual abuse. St. George’s School in Middletown, Rhode Island, has been rocked by allegations that 40 or more former students were raped or sexually abused by staff or fellow students between the 1970s and 2000s. And a graduate of St. Paul’s School in Concord, New Hampshire, was convicted in August of sexually assaulting a 15-year-old freshman in what prosecutors linked to a competition known as the Senior Salute, in which seniors seek to have sex with underclassmen.

The email to Exeter alumni said the school immediately reported the allegations to the appropriate authorities and investigated the claims. Still, MacFarlane acknowledged in a statement given to The Boston Globe that the school’s response was insufficient, and apologized.

The student newspaper, The Exonian, reported at the time of Schubart’s retirement that he decided to step down in December 2011, in the middle of the academic year, for unspecified “personal and medical reasons.”

Among Schubart’s responsibilities at the school was as residential director for the school’s intern program in Washington, the student newspaper reported. In addition to his work at Exeter, he has served as executive director for The Association of Boarding Schools and chairman of the board of the Federation of American and International Schools.

The Association of Boarding Schools honored him in 2012 with an annual leadership award, and he continued his involvement in other educational endeavors, including on the board of a charter school, after his retirement in 2011.

Thomas Hassan, principal from 2009 to June 2015, said in a statement issued by Exeter on Thursday that the school received the 2011 report after he sent an email to the community that year with the goal of encouraging reports of misconduct following cases of sexual abuse at Penn State and Syracuse universities.

He called the report about Schubart “one of the most heartbreaking situations I dealt with as principal.”

Exeter, which has around 1,000 students from 34 countries in grades 9-12, counts among its alumni Facebook’s Mark Zuckerberg. The school has a $1.2 billion endowment and will charge $48,550 per year in tuition and boarding costs next year.