Longest prison sentence served for espionage

The longest prison sentence served following an espionage-related conviction is 28 years 343 days, served by former NSA analyst Ronald Pelton (USA) between his conviction on 16 December 1986 and 24 November 2015. Pelton was arrested by the FBI on 25 November 1985, and confessed to having provided the Soviet Union with details of US intelligence-gathering activities. He was given three concurrent life sentences. Including the time he served on remand before his trial, Pelton was incarcerated for one day short of 30 years.

Pelton began his intelligence career during his stint in the US Air Force in the early 1960s. He was sent to Indiana University to study the Russian language and worked as a signals-intercept operator at a US airbase in Peshawar, Pakistan. In 1965, he joined the National Security Agency (NSA; the US intelligence agency that handles intercepted enemy communications and cryptography). He was a well-regarded intelligence analyst who specialised in data collection management and cryptanalysis (he wrote a book on Soviet cipher systems).

In the late 1970s, Pelton decided to build himself an expensive new home in Howard County, Maryland. Problems with construction led to Pelton and his wife declaring bankruptcy in April 1979. As a person in such dire financial straits is (rightly, it seems) considered a security risk, he lost his job at the NSA in July that same year.

After his departure from the NSA, Pelton's life entered a downward spiral. He took on various odd jobs and get-rich-quick schemes, but made little progress. On 14 January 1980, he called the Soviet Embassy and offered to share information in exchange for money. Although he had no physical documents to offer, he had played a central role in the NSA's intelligence gathering efforts for more than a decade and had an excellent memory. He was able to reveal the existence of major security breaches, including a series of sea-floor wire-taps placed by US submarines as part of Operation Ivy Bells.

He continued to meet with Soviet Intelligence between 1980 and 1985. Soviet agents would debrief him for hours, asking him to use his extensive knowledge of US intelligence gathering operations to explain the confusing and fragmentary pieces of information their sources had provided. In exchange the down-on-his-luck former agent was paid just $35,000.

Pelton was captured following the defection of KGB Officer Vitaly Yurchenko, who recalled meeting with a red-headed former NSA agent when being debriefed by the CIA. He was soon identified and confronted by FBI agents in November 1985. Surprisingly, he confessed to his espionage activities, though he later attempted to retract this confession during his trial.

As of Feb 2020, CIA mole Aldrich Ames has served nearly 26 years of his life sentence, while FBI mole Robert Hanssen has served 19. Another US intelligence mole, Jonathan Pollard (who passed secrets to Israel), was arrested just three days before Pelton and released on parole four days earlier, on 20 November 2015. However, Pollard was not formally convicted until 4 March 1987.

During the Cold War many of those convicted of espionage would be given extremely long sentences, but then released as part of prisoner-exchange arrangements (where one side would swap their captured spies for the others). Few served their full terms. In the Soviet Union and other Eastern Bloc countries, those found to be spying for foreign powers were often swiftly executed rather than jailed.