Story highlights Harold Martin's attorneys had no comment

Client faces 20 counts of illegally possessing national defense information

(CNN) A former government contractor who is accused of stealing thousands of classified and sensitive intelligence files was indicted Wednesday by a federal grand jury in Maryland.

Harold Thomas Martin III, 52, faces 20 counts of willful retention of national defense information.

The indictment alleges Martin removed classified documents from 1996 to 2016. He is accused of keeping documents in his home or car.

The documents include highly classified materials from the National Security Agency, the US Cyber Command, the CIA and the National Reconnaissance Office. Among the documents are ones that reveal US military gaps, capabilities and operations, as well as ones that contained foreign intelligence collection methods, targeting information and technical user materials.

Martin's attorney had no comment when contacted by CNN.

Read More