Former and current students of a Connecticut boarding school have been arrested in connection with a batch of cupcakes befouled with bodily fluids and served to students and staffers, according to reports.

The four teenage suspects — one of whom is a current student at The Gilbert School in the town of Winchester — surrendered Monday, nearly a year after the incident, and were charged with fourth-degree sexual assault, conspiracy to commit fourth-degree sexual assault and second-degree breach of peace, the Hartford Courant reported.

“I’ve never heard of such things,” Winchester Police Chief William Fitzgerald Jr. said Monday, according to the news outlet. “It’s quite unique.”

Police launched a probe last year when they learned that there was something suspicious about some of the cupcakes distributed to students and staffers at the quasi-private high school.

“They were made for certain kids and they were given on a day where they were handing out and certain people got certain ones,” Kelsey Owens, a former student, previously told WFSB.

“The kids they didn’t like got the ones with dashes through the ‘7’ so they knew those were the tainted ones,” Owens said.

Ultimately, a state forensic lab was used to analyze the cupcakes and determined that a foreign substance of human origin had been mixed into the batter.

Fitzgerald declined to be specific about the substance the lab found, but noted that technicians had to perform DNA comparisons of the suspects, according to the Hartford Courant.

Police said they did not believe the substance used to taint the sweet treats was toxic or poisonous, and that no students or staffers became ill from eating them.

The names of the suspects were not released due to their ages at the time of the incident.