A Silver Spring man who worked as a linguist for the FBI was sentenced Monday to 20 months in prison for leaking secret documents to a blogger.

But federal prosecutors in Maryland have remained mum about exactly what was contained in the classified papers that Shamai K. Leibowitz, 39, gave the unnamed blogger in April 2009, while he worked on contract for the FBI. According to court records, the documents concerned "communication intelligence activities."

During a Monday hearing in U.S. District Court in Greenbelt, Assistant U.S. Attorney Steven M. Dunne said Leibowitz "betrayed the FBI when he worked there," but offered no details.

U.S. District Judge Alexander Williams Jr. said the response of federal authorities convinced him Leibowitz committed a "very, very serious offense." But the judge said even he does not know what information Leibowitz, a Hebrew scholar, disclosed...

...Leibowitz, who worked as a lawyer in Israel and has dual U.S. and Israeli citizenship, said in court papers that he worked for the U.S. State Department in 2006, teaching Hebrew and Israeli law and culture to American diplomats. He said he then was hired as a contractor by the U.S. Department of Defense at its Defense Language Institute.

According to court papers, Leibowitz worked on contract for the FBI from January through August 2009.

In court Monday, Leibowitz said he made a mistake. But he said that, at the time he revealed the classified information, he believed the documents showed a "violation of the law." He said he should have pursued other options within the government to report his concerns.