Federal prosecutors on Tuesday closed their investigation into Lower Merion School District's secret use of software to track student laptops, saying they found no evidence that anyone intentionally committed a crime.

The decision, announced by U.S. Attorney Zane Memeger, ended a six-month probe by the FBI into allegations that district employees might have spied on students through webcams on their school-issued laptops.

In a brief statement released by his office, Memeger didn't disclose details of the investigation, but said agents and prosecutors concluded that charges were unwarranted.

"For the government to prosecute a criminal case, it must prove beyond a reasonable doubt that the person charged acted with criminal intent," his statement said. "We have not found evidence that would establish beyond a reasonable doubt that anyone involved had criminal intent."

The announcement represented an unusual step for federal investigators. The FBI and U.S. Attorneys' offices rarely acknowledge when they begin or end a criminal inquiry.

Memeger's predecessor, Michael Levy, disclosed the probe in February because of the community interest and visibility in the allegations, he said at the time. Memeger's announcement on Tuesday was intended "to close at least one part of this matter" before the new school year opens, he said.

His decision came a day after the Lower Merion School Board adopted new policies governing how, when and why staff will track the take-home laptops Lower Merion issues to every high school student.

Henry E. Hockeimer Jr., a lawyer for the school district, welcomed the news.

"The district is certainly gratified that after a hard look into this matter, the FBI and United States Attorney have concluded that no criminal conduct occurred," Hockeimer said.

He noted that it was consistent with the findings of internal investigation that he supervised earlier this year.

The FBI probe included interviews with the two school district information technology employees who were suspended with pay when the laptop tracking program came to light in February. Both had the authority to activate the laptop tracking software and access webcam photos, though have denied any wrongdoing.

The district has maintained that technicians used the software only to find lost or missing laptops, but acknowledged that staffers often forgot to turn off the tracking system after they turned it on.

Hockeimer declined to say whether either suspended employee will return to work this fall, saying it was a personnel matter.

Meanwhile, two civil lawsuits over the laptop monitoring program remain unresolved. Both were filed by students who claim the district invaded their privacy by secretly snapping hundreds of webcam photos, including shots of them inside their homes.

The students' attorney, Mark S. Haltzman, said the prosecutors' decision bolstered the need for new laws. He noted legislation proposed by U.S. Sen. Arlen Specter (D., Pa.) that would expand wiretap laws to cover technology such as laptop webcams.

"The inability of the federal government to prosecute those persons involved in the spying on the LMSD students and their families through school issued laptops underscores the importance of Sen. Specter's efforts to amend the criminal statutes to close the loop holes in our current laws," Haltzman said.

Contact staff writer John P. Martin at 610-313-8120 or jmartin@phillynews.com.