WASHINGTON — A former National Security Agency employee pleaded guilty Friday to keeping top secret U.S. defense material at his home — the latest in a series of breaches involving workers at the nation’s largest spy shop.

Nghia Hoang Pho, 67, of Ellicott City, Maryland, pleaded guilty to willful retention of national defense information, according to federal law enforcement officials.

The guilty plea said that between 2010 and March 2015, Pho removed and retained at his home paper and digital copies of U.S. government documents and writings containing national defense information.

Starting in April 2006, he worked as a developer in the National Security Agency’s Tailored Access Operations unit, which is involved in cyber operations.

The charges carry a maximum sentence of 10 years in prison, followed by three years of supervised release. His sentencing is set for April 6.

The guilty plea was announced by Stephen Schenning, acting U.S. attorney for the District of Maryland; Dana Boente, acting assistant attorney general for national security; and Gordon Johnson, special agent in charge of the FBI’s Baltimore Field Office.

Former NSA contractor Edward Snowden disclosed a cache of classified material in 2013 exposing U.S. government surveillance programs.

In August 2016, Harold Thomas Martin III, 51, of Glen Burnie, Maryland, was arrested by the FBI after federal prosecutors said the former NSA contractor illegally removed highly classified information and stored the material in his home and car.

Reality Winner, 25, a former Air Force linguist who worked as an NSA contractor at a facility in Augusta, Georgia, was charged in June with copying a classified U.S. report and mailing it to a news organization.