During the 1930s Nikolai Yezhov was one of Stalin's most powerful officials. In 1936 he was appointed People's Commissar for Internal Affairs, in which position he led brutal purges, causing him to be widely feared. Yezhov can be seen in the top photo (undated, but probably from the mid 1930s), strolling along the Moscow-Volga Canal with Stalin, Defense Commissar Kliment Voroshilov and Premier Vyacheslav Molotov. Yezhov is on the far right beside Stalin.

But Yezhov's violent methods eventually provoked a backlash, and in the late 1930s he fell out of favor. He was arrested in 1939 and executed in February 1940. In a subsequently released version of the Moscow-Volga canal photo (bottom), Yezhov was no longer present. He had been removed by political censors.

This pair of images gave its name to The Commissar Vanishes, a book (and later museum exhibit) by David King that explores the history of Soviet photo falsification. It has become one of the most famous examples of how totalitarian regimes often doctor photos in an attempt to rewrite history.