(Kacper Pempel/Reuters)

A National Security Agency employee who worked at home without authorization on sensitive hacking tools was sentenced to more than five years in prison Tuesday, prosecutors said.

In December, Nghia Hoang Pho, 68, of Ellicott City, Md., pleaded guilty to willful detention of national defense information. A developer in the NSA’s Tailored Access Operations, the agency’s elite hacking unit, he took classified material in hard copy and digital form home between 2010 and 2015.

On Tuesday, Pho was sentenced to 66 months in prison, according to a news release from the U.S. attorney’s office for the District of Maryland.

“Removing and retaining such highly classified material displays a total disregard of Pho’s oath and promise to protect our nation’s national security,” U.S. Attorney Robert K. Hur said in a statement. “Pho compromised some of our country’s most closely held types of intelligence, and forced NSA to abandon important initiatives to protect itself and its operational capabilities, at great economic and operational cost.”

Pho’s case, one of many significant NSA breaches, was also noteworthy because he was using Kaspersky Lab anti-virus products — software from a Russian firm the agency never used for fear that it could facilitate spying.