Spying for other countries or groups is in many cases illegal and punishable by law. The following is a list of individuals that have either been imprisoned for spying, or individuals that have been arrested in connection to their spying activities.
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| Name | Nationality | Summary | Conviction Date | Penalty |
|---|---|---|---|---|
| Aldrich Ames | American | Convicted of spying for the Soviet Union and Russia | 1994 | Life sentence (without parole) |
| David Sheldon Boone | American | Sold secret documents to the Soviet Union and is estimated to have received $60,000 from the KGB | February 26, 1999 | 24 Years and 4 Months |
| Marthe Cnockaert | Belgian | Convicted for spying for the United Kingdom and its allies during the First World War | November 1916 | Life sentence (released 2 years later) |
| Clayton J. Lonetree | American | Convicted for providing classified information to the Soviet Union while stationed in Moscow as a guard at the U.S. Embassy | August 21, 1987 | 30-year sentence, reduced to 15, released February 1996 |
| Alexander Fishenko | American-Russian | Convicted for illegally exporting microelectronics from the U.S.A. to Russia | July 21, 2016 | 10-year sentence [1] |
| James Hall III | American | Signals analyst who sold eavesdropping and code secrets to East Germany and the Soviet Union from 1983 to 1988 | July 20, 1989 | 40-year sentence |
| Robert Hanssen | American | Spied for Soviet and Russian intelligence services against the United States from 1979 to 2001 | July 6, 2001 | Life sentence (without parole) |
| Ana Montes | American | Convicted for conspiracy to commit espionage for the government of Cuba | October 2002 | 25-year prison term followed by five years probation |
| Harold James Nicholson | American | Twice-convicted spy for Russia's Foreign Intelligence Service | June 5, 1997 | 23 years 7-month sentence |
| Stewart Nozette | American | Convicted for attempted espionage and fraud against the United States for the government of Israel | 2009 | 13-year sentence |
| Ronald Pelton | American | Spied for and sold secret documents to the Soviet Union. Was known to have a photographic memory and as such never passed any physical documents on. | 1983 | Life sentence (Released November 24, 2015) |
| Earl Edwin Pitts | American | Accused of spying for the Soviet Union and Russia, and pleaded guilty to conspiring and attempting to commit espionage | 1997 | 27-year sentence |
| Jonathan Pollard | American | Convicted for espionage for passing highly sensitive classified information to Israel while working as an American civilian intelligence analyst | 1987 | Life sentence (Released November 20, 2015) |
| George Trofimoff | American | Convicted for spying for the Soviet Union during the 1970s and 1980s | September 27, 2001 | Life sentence |
| John Anthony Walker | American | Convicted of spying for the Soviet Union from 1968 to 1985 | 1985 | Life sentence |
| Brian Patrick Regan | American | Convicted of one of gathering national defense information and two counts of attempted espionage for soliciting classified information to Iraq, China, and Libya. | March 21, 2003 | Life sentence |
| Chelsea Manning | American | Convicted of six counts of the espionage act for providing classified information to Wikileaks | July 30, 2013 | 35-year sentence, commuted (released May 17, 2017) |
| Dongfan "Greg" Chung | Chinese | Convicted of economic espionage; stole trade secrets related to the US Space Shuttle program and the Delta IV rocket and provided them to China [2] | July 16, 2009 [2] | 15-year sentence, died May 18, 2020, while incarcerated [3] |
| Kendall & Gwendolyn Myers | American | Convicted of spying for Cuba across a 30-year span | November 20, 2009 | Life sentence (without parole); 81 months |
A guy named James Durward Harper was caught spying for Poland in October 17 1983, In Mountainview, California which ended up in Russian hands. The material was focused on Minute Man missiles procured through his wife, Ruby Schuler, at her workplace at Control Systems Inc..