An Israeli-American former FBI linguist pled guilty Thursday to unlawfully passing on classified documents to an unidentified blogger, the US Department of Justice announced. The FBI contract worker, 39-year-old Shamai Kedem Leibowitz of Maryland, who also went by the name Samuel Shamai Leibowitz, admitted that he disclosed five FBI documents classified as "secret" concerning the communication intelligence activities of the United States, according to the Justice Department. It is unclear what specific information he passed on as part of his illicit activities, which the Justice Department said took place between January and April of this year. As worked out in the plea agreement, he is set to serve 20 months in prison. "The willful disclosure of classified information to those not entitled to receive it is a serious crime," said David Kris, assistant attorney general for national security, in a statement put out by the US Department of Justice. "Today's guilty plea should serve as a warning to anyone in government who would consider compromising our nation's secrets. "As a trusted member of the FBI ranks, Leibowitz abused the trust of the FBI and the American public by using his access to classified information for his own purposes," said Special Agent in Charge Richard McFeely in the same statement. Neither Leibowitz nor his attorney could be reached for comment by The Jerusalem Post. According to the Jewish Telegraphic Agency, Leibowitz also has a past as a far-left Israeli peace activist who favored a one-state solution to the Israeli-Palestinian conflict. Additionally, he is a grandson to Yeshayahu Leibowitz, the Orthodox Israeli philosopher who spoke out against Israeli's occupation of the West Bank and the Gaza Strip. According to Leibowitz's blog, he is a certified Hebrew-English translator and a lawyer able to work in New York and Israel. On his Web site, he attributes his favorite quote to Albert Einstein: "Laws alone can not secure freedom of expression; in order that every man present his views without penalty there must be spirit of tolerance in the entire population."