CONCORD, N.H. — St. Paul’s School boasts a glittering roster of alumni that includes members of Congress, a Nobel laureate and the current secretary of state. The elite prep school also allegedly has a sordid tradition of sexual conquest where graduating boys try to take the virginity of younger girls.

Details of a practice authorities say was called the “Senior Salute” were spelled out in stark terms by a former prefect at the New Hampshire school who is charged with raping a 15-year-old girl on the roof of a campus building in May 2014.

Owen Labrie, now 19, has pleaded not guilty to several felonies. When his trial begins Monday, prosecutors are expected to call current and former students to testify about the sexual culture at the school.

Labrie, of Tunbridge, Vermont, talked openly about the tradition when he was interviewed by Concord police. On a campus where upperclassmen studiously avoid their younger peers in most settings, Labrie told a detective some students “take great pride” in having sex with younger students.

Labrie also told the detective of a contest where boys compete to “score” with the most girls, keeping a running tally written in marker on a wall behind washing machines. The school kept painting over the scoreboard so it eventually was moved online. He told the detective he was “trying to be number one.”

A counselor also told an investigator about the tradition, the Concord Monitor reported last year, citing a police affidavit. The same affidavit said the school had been trying to educate students against “sexual scoring.”

A student leader honored at graduation – two days after the alleged assault – with the Rector’s Award for “selfless devotion to school activities,” Labrie was accepted to Harvard but the school said in September that he is no longer enrolled. He told the detective that he tried to educate other students not to engage in “Senior Salute” and that the school wasn’t doing enough to curtail the tradition.

“The school has to put its foot down on this culture,” Labrie is quoted in an affidavit. “It’s not healthy.”

Founded in 1856, St. Paul’s is an Episcopal school nestled on 2,000 pastoral acres on the outskirts of downtown Concord, New Hampshire’s capital. Tuition, room and board currently clocks in at $53,810.

The school belongs to the Eight Schools Association, a sort of Ivy League for prep schools.

Secretary of State John Kerry graduated from St. Paul’s in 1962, alongside former FBI Director Robert Mueller. Doonesbury creator Garry Trudeau is an alum as are 13 U.S. ambassadors, three Pulitzer Prize winners and sons of the Astor and Kennedy families.

Labrie’s lawyer, J.W. Carney Jr., represented convicted mobster James “Whitey” Bulger a couple of years ago.

Prosecutors say Labrie took his victim by surprise. He is charged with three counts of aggravated felony sex assault, endangering the welfare of a child and using a computer to lure the girl to the on-campus meeting.

Labrie denied having intercourse with the girl, telling police that they partially disrobed, kissed and touched. He also acknowledged putting on a condom. Labrie said the freshman girl was eager to have sex, but the aspiring divinity student said he had a “moment of self-restraint” and stopped.

Asked why the girl would lie about having sex with him, Labrie said it’s a “great source of pride for younger students” to have sex with seniors.