Norwich — Kelly Middle School Principal William Peckrul said he will resign June 30, citing personal reasons, and the district is searching for a new principal at the school with a troubled reputation for behavioral problems as it prepares to convert to a science and technology magnet middle school for grades six through eight.

Peckrul submitted his letter of resignation to Superintendent Abby Dolliver on May 29, two days before a 14-year-old girl was arrested at Kelly on Thursday, May 31, on charges of third-degree assault and breach of peace. The arrest came after an alleged assault on an eighth-grade boy whose father had made repeated complaints to the school that his son was being bullied throughout the year.

Peckrul, who did not return phone calls Tuesday seeking comment on his resignation, has served as Kelly principal for the past seven years, starting when the school was a traditional sixth- through eighth-grade middle school. In 2014-15, Kelly was converted into the city’s only school for seventh- and eighth-graders.

“It has been an honor to serve as the leader of (Kelly) for the past seven years,” Peckrul wrote in the letter, “but I feel for personal reasons it is in my best interest to step down from that position. I am grateful for the opportunity to serve you and the students and families of Norwich and look upon that experience with great pride.”

Teachers, parents, school officials and youth advocates have acknowledged the behavioral problems at the school that enrolls more than 700 seventh- and eighth-graders. More budget cuts led the school board to eliminate school resource police officers. Last year, Kelly hired a school safety officer to try a different approach to improve student behavior.

But complaints continued this school year. Timothy Wilcox, the father of the alleged victim in last week’s assault, said he and his wife had called the school more than 30 times during the school year to complain about bullying.

Next year, Kelly will return to the sixth- to eighth-grade format with a grant-funded science, technology, engineering, arts and math (STEAM) intradistrict magnet middle school. Teachers Memorial School, now a sixth-grade academy, also will be a sixth- through eighth-grade magnet school, with a global studies theme.

Dolliver said Kelly still will have nearly 700 students next year, as the larger of the two city middle schools. After the lottery selections are made, Kelly will have about 230 students per grade level. Teachers Memorial, a smaller building, has a cap of 420 students, Dolliver said.

“Mr. Peckrul has decided to move on,” Dolliver said of the resignation. “We appreciate the time he’s been here.”

The Kelly principal position has been posted on education employment websites and the school system’s webpage. Applications are due by June 15. Dolliver said a committee of school board members, parents and staff will review the applications and assist with the selection process.

Dolliver hopes to have a new principal on board by July 1.

c.bessette@theday.com