Concord — The head of St. Paul’s School this week answered the question of why page 103 of the 2016-17 yearbook was changed prior to graduation in a letter to the school community.

St. Paul’s Rector Michael Hirschfeld wrote on Monday that residents of an all-boys dormitory were wearing crowns, which were the subject of an ongoing internal investigation. The school initiated that investigation to determine if the crown was part of a sexual competition, officials said.

As a result, St. Paul’s administrators viewed the picture as “inappropriate,” Hirschfeld told parents, students, faculty and staff. He explained that the school asked the yearbook publisher to produce a new yearbook page, which could be pasted over the original page.

A corresponding yearbook page highlighting the same dormitory shows a group of boys posing for a picture with one of them holding a yellow Buffalo Wild Wings crown. That page did not have anything placed over it.

Last week, the New Hampshire Attorney General’s Office cited the crown as one of several reasons for launching a criminal investigation into the elite Concord boarding school. The investigation will focus on the school’s response to several reports of sexual misconduct and whether St. Paul’s endangered the welfare of children or broke a law that prohibits the obstruction of criminal investigations.

The crown was first described to the Concord Monitor by people connected with the institution as part of a game of sexual conquest among students.

In his letter on Monday, Hirschfeld said the school discovered no evidence of competition.

“The investigator found that the boys were not competing nor soliciting sexual relationships in order to be listed on the crown,” he wrote.

Boys’ names were written on the crown to document their relationships, although no girls were named, Hirschfeld said.

The school determined that the students’ behavior violated school rules but not New Hampshire law.

“Five students were found to be in violation of the school’s prohibition of recording relationships,” Hirschfeld wrote.

School officials declined to say why boys had recorded their relationships on the crown.

The school disciplined five students, ranging from suspension to dismissal, St. Paul’s officials said.

In his letter, Hirschfeld opened by sharing his response to the attorney general’s announcement on Thursday. He wrote that he was “startled and saddened” to learn about the probe, and that he continues to be proud of St. Paul’s students, staff and faculty for all they’ve accomplished. He cited numerous examples of how he believes the school community has taken steps to improve the culture at St. Paul’s, such as by engaging in conversations about gender identity and healthy relationships.

State prosecutors are working with the Merrimack County attorney, New Hampshire State Police and the Concord Police Department to investigate the elite boarding school. The task force will look at decades of reports to include not just recent cases of sexual misconduct at the school, but also past sexual abuse of students by faculty and staff.

A report released by St. Paul’s this May substantiates claims against at least 13 former staff members at the school between 1948 and 1988. The yearlong investigation — commissioned by St. Paul’s and carried out by a former Massachusetts attorney general — found that teachers repeatedly took advantage of the teenagers in their care. Allegations range from boundary violations, such as love letters, to rape.

The state’s top prosecutors also will review evidence from the high-profile trial of Owen Labrie, of Tunbridge. The national spotlight fell on St. Paul’s in 2014 when Labrie was arrested and charged with sexually assaulting a 15-year-old freshman as part of a sexual conquest game known as the “Senior Salute.”

Upperclassmen solicited intimate encounters from younger pupils in what was referred to as a springtime ritual.

Labrie was convicted in August 2015 on three counts of statutory rape and one count of endangering the welfare of a child, all misdemeanors.

The jury also found him guilty of prohibited use of a computer, a felony that requires lifelong registration as a sex offender. His appeal is before the New Hampshire Supreme Court.