The mother of a former seventh-grade member of the St. Augustine High School marching band has sued the school and its principal on the boy’s behalf, claiming negligence in failing to prevent a student-on-student sexual assault last year during a trip to Florida for a Martin Luther King Jr. Day parade performance.

The lawsuit, filed Friday in Orleans Parish Civil District Court, claims the all-boys Catholic school on A.P. Tureaud Avenue and its principal, Sean Goodwin, failed to ensure the safety of the boy, resulting in a sexual assault by another minor student in a hotel room on Jan. 18, 2015.

Afterward, the lawsuit says, school officials showed a “reluctance to address the situation,” leading the victim to drop out of school and “surrender his dream of being a member of the St. Augustine band.”

The suit does not specify a dollar figure for requested damages. It says the boy has suffered “emotional distress, and intrusive thoughts related to being sexually assaulted by another male student.”

Now 13, he “has exhibited classic symptoms of post-traumatic stress disorders, and other emotional challenges,” the lawsuit states.

The New Orleans Advocate does not identify victims of alleged sexual assaults.

A spokeswoman for St. Augustine said she could not immediately comment on the lawsuit.

The Marching 100 Purple Knights Band was visiting St. Petersburg, Florida, for that city’s 30th annual Martin Luther King Jr. weekend celebration, staying four to a room when the assault took place the evening before the parade, said the family’s attorney, Garron Johnson.

One fellow band member was sleeping and another was in the shower when a third student raped his client, Johnson said.

The boy told his mother about it on the bus ride home, and she contacted the school, but what happened next is unclear, Johnson said.

“We’re not 100 percent sure if it was reported to authorities in Florida because everything is a juvenile matter. It’s very difficult to get firsthand information,” he said.

The boy dropped out of school within days, and Johnson said St. Augustine expelled the student accused of the sexual attack.

His client did not seek medical attention, Johnson said, and school officials offered no counseling.

Discussions with the school since then have proven fruitless, Johnson said.

“They’re just stonewalling,” he said. “We’re contending that there was not enough parental supervision. You don’t leave kids under the age of 13 in a room to manage by themselves. Had there been proper adult supervision, this would have been avoided.”

He said his client “dreamed about going to St. Aug to be in the band. Not only was he violated sexually, but his dreams were also violated.”

Louisiana law requires school staff members to report allegations of child abuse or neglect. Goodwin did not accompany the band for the Florida trip, Johnson said.

Follow John Simerman on Twitter, @johnsimerman.