In 1975, Putin joined the KGB and trained at the 401st KGB school in Okhta, Leningrad.[13][29] After training, he worked in the Second Chief Directorate (counter-intelligence), before he was transferred to the First Chief Directorate, where he monitored foreigners and consular officials in Leningrad.[13][30][31] In September 1984, Putin was sent to Moscow for further training at the Yuri Andropov Red Banner Institute.[32][33][34] From 1985 to 1990 he served in Dresden, East Germany,[35] using a cover identity as a translator.[36] Masha Gessen, a Russian-American who has authored a biography about Putin, claims "Putin and his colleagues were reduced mainly to collecting press clippings, thus contributing to the mountains of useless information produced by the KGB".[36] According to Putin's official biography, during the fall of the Berlin Wall that began on 9 November 1989, he burned KGB files to prevent demonstrators from obtaining them.[37]