PHILADELPHIA -- No criminal charges will be filed against a suburban Philadelphia school district that secretly snapped tens of thousands of webcam photographs and screen shots on laptops issued to students.

The FBI and federal prosecutors announced Tuesday they could not prove any criminal wrongdoing by Lower Merion School District.

"We have not found evidence that would establish beyond a reasonable doubt that anyone involved had criminal intent," U.S. Attorney Zane Memeger said in a statement.

The FBI investigated the wealthy district for possible wiretap violations after a student's civil lawsuit brought the issue to the public's attention. Lower Merion High School student Blake Robbins alleged that the district took photographs of him in his bedroom as he slept.

None of the images captured appeared to be salacious or inappropriate, school officials have said.

District officials initially said its technology staff only activated the remote tracking system to try to find laptops that had been reported lost or stolen.

But the district soon acknowledged that the software system sometimes remained activated for weeks or months, even after a laptop was found, causing the district to capture 56,000 web-cam photographs and screen shots from student laptops.

"We are very pleased with today's decision by the U.S. attorney's office, which supports the findings of our internal investigation," Superintendent Christopher McGinley said. "This is all good news for the students and staff of Lower Merion School District as we prepare for the start of a new school year."

The federal prosecutor's announcement follows a school board decision Monday to prohibit remote activation of the tracking software without the written consent of students and their parents or guardians. The policy was recommended by a task force formed in the wake of the lawsuit.

Robbins' lawsuit is pending, and a second student has joined him in suing the district over the tracking program.

Robbins maintains that he never reported his laptop missing or stolen, and doesn't know why the district deployed the surveillance software on his computer.