Norwich — The family of a 14-year-old boy allegedly assaulted at the Kelly Middle School at the end of May has filed a federal complaint against the Norwich school system for violating the boy’s civil rights.

The U.S. Department of Education’s Office of Civil Rights opened an investigation into the complaint for “possible disability-based discrimination” on June 28, a department spokesman confirmed Monday. The department could not comment further, because the investigation is ongoing.

The boy, Bryan Mossor, has a learning disability, his father, Timothy Wilcox, said. The incident on May 31 led to the arrest of a 14-year-old girl by Norwich police on charges of third-degree assault and breach of peace. Police said the girl jumped the boy twice in the Kelly hallway, punched him and knocked him to the floor.

Wilcox said the incident was the culmination of two years of repeated bullying by various students at the seventh-and-eighth-grade school. Wilcox said he and the boy’s mother had called school administrators more than 30 times during the past school year to complain about the bullying, but school officials failed to do anything to stop it. Wilcox said Mossor will attend Norwich Free Academy starting in August, and his son expects to do well at his new school.

Mossor said he was bullied and teased repeatedly about everything from his shoes to his hair and “a lot of other stuff.”

Wilcox also said Monday he included in his federal complaint an allegation that several days after the incident and arrest, Kelly Principal William Peckrul — who resigned at the end of June, citing personal reasons — told Mossor to call his father and tell him the issue had been resolved, when Wilcox said nothing had been done.

Wilcox said Monday he was contacted by the U.S. Department of Education office in Boston, which is handling the investigation, and was told the school system is willing to negotiate a possible settlement before the investigation is completed.

Wilcox said while he will ask his attorney to negotiate with school officials, he has strong demands he wants included in the settlement, including Superintendent Abby Dolliver’s resignation and admission by the school system of criminal wrongdoing for failing to protect his son’s safety.

“I want the school held criminally responsible, because I have complained over and over and over,” Wilcox said. “… And I also want some kind of financial responsibility on them for not protecting my son’s safety.”

He also wants written assurance that the school system has changed its bullying policies.

Dolliver said Monday she received confirmation of the federal complaint and said the school system would investigate the complaint as it would any other complaint against the school system.

Norwich does not have school resource police officers. At the start of last school year, a school safety officer was hired for Kelly, and a second one was added mid-year, Dolliver said. School safety officers are not police officers.

“We did a lot to try to improve student safety at Kelly,” she said.

This summer, the school is converting to a sixth-through-eighth-grade magnet middle school with a science, technology, engineering, arts and math theme.

School officials conducted the first round of interviews for a new Kelly principal last week and will bring back finalist candidates on Friday for a second interview.

According to the Office of Civil Rights complaint procedure posted on its website, the department would facilitate settlement negotiations if the parties agree to attempt to resolve the complaint.

The office’s investigation could include reviewing documents submitted by both parties, interviews with Mossor and his family, school personnel and other witnesses and possible site visits. If sufficient evidence of a violation is found, the office would attempt to negotiate a voluntary agreement with the school system that would describe a specific remedial action plan, which would be monitored by OCR staff.

c.bessette@theday.com