At least 11 former Episcopal Academy students have come forward to say they were sexually abused decades ago by a teacher there, the school has disclosed, but the accusations are unlikely to be prosecuted.

The former fourth-grade teacher, Richard Perkins Smith, 67, of Media, taught at Episcopal's Devon campus from 1970 to 1990 and later served in the school's administration.

He is awaiting trial in Massachusetts on charges including child rape and indecent assault. Smith is accused of sexually assaulting four boys, ages 11 to 15, at a Cape Cod summer camp more than 30 years ago.

In a 2012 interview with Massachusetts investigators, Smith admitted he had once molested an Episcopal student and that he had confessed the incident at the time to the head of the school, according to court documents.

That led school officials and local authorities to search for more victims. In April 2013, Episcopal contacted students, alumni, and parents from Smith's classes, including pupils who never graduated from the school, according to a letter it sent this month to the school community.

"We were devastated to learn through our review about the extent of Smith's conduct, which we now understand involved at least eleven former Episcopal students," the letter said.

It was signed by T.J. Locke, head of the school, and Edward H. Vick, chairman of the board of trustees.

A spokeswoman at Episcopal on Tuesday said officials would have no additional comment.

James "Jay" Crawford, the retired headmaster who ran the school during Smith's tenure, declined to comment when reached at his home Tuesday.

Montgomery County prosecutors said they have closed the investigation, in part because of the statute of limitations on the alleged crimes.

"There is not a case we can prosecute at this point," First Assistant District Attorney Kevin Steele said Tuesday.

After teaching, Smith worked on fund-raising in Episcopal's development office until 1998.

In May 2013, Smith was charged with sexually abusing a child in Delaware County after investigators allegedly identified a victim in a video from a computer seized from Smith's Middletown Township home. A warrant for Smith's arrest in that case has been issued for his return to Delaware County once the Massachusetts case is concluded.

In 2008, Episcopal consolidated all classes from its lower school in Devon, Chester County, and a larger campus on City Avenue in Merion, Montgomery County, to a 123-acre campus in Newtown Square. The school serves about 1,200 students in pre-kindergarten to 12th grade.