A former imagery scientist at the U.S. National Geospatial-Intelligence Agency is headed to jail for taking more than 500 pages of classified documents.

Mohan L. Nirala, 52, of Laurel, Maryland, received a 12-month and one-day sentence on March 10 after pleading guilty to willful retention of national defense information.

Nirala worked at NGA from 2009 to 2015, but according to court testimony posted on cryptome.org, came under investigation in 2013 for removing classified materials from NGA headquarters in Springfield.

The agency suspended Nirala’s security clearance in 2014, and a week later FBI agents uncovered more than 20 classified documents while executing a search warrant of his home, which he claimed not to have, according to Department of Justice officials.

Two years later, on March 8, 2016, law enforcement officials arrived at Nirala’s home to execute an arrest warrant. Upon finding him in the basement of his home, federal agents also discovered a box containing more than 500 pages of Secret and Top Secret material.

Nirala pleaded guilty on Sept. 16, 2016, and was sentenced in the U.S. District Court for the Eastern District of Virginia.