Russian nuclear submarines and missile warning systems, analysed and provided it to a British consulting firm. He steadfastly denied using any classified information and ISKAN is said to have no access to Russian classified materials. Sutyagin maintained his innocence throughout his trial and conviction, but had to plead guilty shortly before the swap to qualify for a Presidential pardon. The U.S. Department of State and Amnesty International classified Sutyagin as a political prisoner, not a spy. The Washington Post commented that Sutyagin's case differed from the other released prisoners, and that his original arrest might have been to warn Russians not to cooperate with Western companies and think tanks. According to his relatives, Sutyagin phoned home on his arrival in the UK, saying that he was placed in an undisclosed location in a London suburb and that British authorities were in the process of granting him a UK visa. Later his lawyer confirmed that Sutyagin was granted leave to remain in the UK. Sergei Skripal Sergei Skripal was a colonel in Russia's Military Intelligence Service (GRU), who was arrested and convicted of high treason in Russia in 2006, and sentenced to 13 years in prison. According to the prosecution, he had spied for the United Kingdom's MI6 as a double agent. After the prisoner exchange in 2010, he moved to the UK and in 2018 Skripal and his daughter Yulia were poisoned with a nerve agent in Salisbury, England. Three unrelated people were accidentally poisoned as well, one of them fatally. Aleksandr Zaporozhsky Alexander Zaporozhsky was an operative in Russia's Foreign Intelligence Service. He was sentenced in 2003 to 18 years for secret cooperation with the United States. He was released as part of the swap after serving seven years. Gennady Vasilenko Gennady Semyonovich Vasilenko () is the only person swapped from the Russian side who was not convicted on espionage (high treason) charges. He was a KGB officer who worked for external intelligence and counter-intelligence departments during the 1970s and 1980s. In 1988, presumably having been fingered by a Russian mole in the FBI, Robert Hanssen, he fell under suspicion of being a double agent. Vasilenko was not convicted but instead sacked from the KGB. He was arrested in 2005 and charged with an attempted murder. Due to lack of evidence this charge was dropped. Instead, he was sentenced to three years for possession of illegal firearms and explosive