In March 1992 Mitrokhin, age 69, walked into the British embassy in Riga and asked to see a member of the British Secret Intelligence Service. He had arrived on the overnight train from Moscow and spoke no English, but explained that he had joined the KGB in 1948, and that from late 1956 until his retirement in 1984 he had been in charge of the KGB’s archives at the First Chief Directorate’s headquarters at Yasenevo. For the previous 25 years, since the premature conclusion of his only overseas assignment, to Israel, he had supervised the tens of thousand of files that had been accumulated by the world’s largest and most feared intelligence agency, and he had taken the opportunity to read many of the most interesting ones. For 12 of those years, and much of his retirement, he reconstructed his own version of what he regarded as the most significant dossiers, documenting Josef Stalin’s crimes and the many misdeeds committed in the name of Soviet Communism. For most of his career, he said, he had been disenchanted with the Soviet system, had listened to Western radio broadcasts, and read dissident literature.
In 1972, when he was made responsible for checking the First Chief Directorate files being transferred from the old headquarters in the Lubyanka Prison to the KGB’s modern building on the outskirts of Moscow, he embarked on an illicit history of the Soviet Union’s most secret operations. Mitrokhin asserted that he had simply copied the original files and walked out of the heavily guarded KGB compound with his handwritten notes stuffed into his socks. He had then rewritten a detailed account of the files from his scraps of paper into exercise books and other convenient binders, which he had hidden in a milk churn concealed under his country dacha. In return for political asylum for himself and his family, he offered his entire collection, amounting to a full six cases of documents. He returned to Riga on 9 April with more samples of his handiwork and was met by SIS officers who examined some 2,000 sheets of his archive and scrutinized his party membership card and his KGB retirement certificate.
Acknowledging the authenticity of what he had shown them, a further appointment was made two months hence to meet the man now code-named GUNNER by the SIS, and on 11 June he returned to Riga carrying a rucksack containing yet more material.
Mitrokhin subsequently made a second journey to Riga on the anniversary of the Bolshevik revolution, accompanied by his wife and son, and an SIS officer later visited his empty dacha outside Moscow and recovered his secret hoard of papers and carried them undetected to the British Embassy. Now code-named JESSANT, no official announcement was made of Mitrokhin’s defection, and in the chaos of 1992, his disappearance from the Russian capital probably went unnoticed.
In the months that followed, numerous counterintelligence operations were mounted across the globe. Near Belfauz, Switzerland, booby-trapped caches of weapons and covert radio equipment were dug up in the forest. In Tampa, Florida, retired U.S. Army colonel George Trofimoff was approached by Federal Bureau of Investigation special agents posing as Russian intelligence officers, to whom he admitted in a secretly videotaped meeting lasting six hours that he had spied for the Soviets for 25 years since his recruitment in Nuremberg in 1969; code-named ANTEY, MARKIZ, and KONSUL in Mitrokhin’s files, Trofimoff was the most senior U.S. Army officer ever charged with espionage. In Australia a senior Australian Security Intelligence Organisation analyst was identified as a long term source for the KGB, although he was not arrested. In a Virginia motel, Robert Lipka, a former National Security Agency cryptographer, code-named DAN by the KGB, was arrested; in September 1997 he was sentenced to 18 years’ imprisonment. The information supplied by Mitrokhin was considered so valuable that the CIA paid the SIS an estimated $1 million for his assistance. Ironically, the CIA had rebuffed his original approach to them in Riga, on the grounds that his material was of only historical and not current operational relevance. Mitrokhin’s offer to the CIA’s station in Riga had been rejected by the local station chief who never received a reply to a cable to the CIA’s SE Division.
Mitrokhin’s files were transformed into two books, the first of which was published in 1999 as The Mitrokhin Archive with Professor Christopher Andrew of Cambridge University. It identified Melita Norwood and John Symonds as having been important Soviet agents. The second volume was released in 2005, two years after Mitrokhin’s death.