Markus Hess, a German citizen, is best known for his endeavours as a hacker in the late 1980s.
Alongside fellow hackers Dirk Brzezinski and Peter Carl, Hess hacked into networks of military and industrial computers based in the United States, Europe and the East Asia, and sold the information to the Soviet KGB for US$54,000.
During his time working for the KGB, Hess is estimated to have broken into 400 U.S.
military computers.
The hacked material included "sensitive semiconductor, satellite, space, and aircraft technologies".