叶群
Later in 1971 a Soviet medical team secretly traveled to the crash site and exhumed the bodies, which were by then modestly decomposed. The team removed the heads of two of the corpses suspected to be Lin Biao and Ye Qun and took them back to Russia for forensic examination. In 1972 the team concluded the heads belonged to Lin Biao and Ye Qun (the heads are still stored in Russian archives). In order to corroborate their findings the team returned to Mongolia a second time to inspect the body believed to be Lin Biao's. After exhuming the body a second time the team found the corpse's right lung had the remains of tuberculosis, which Lin had suffered from, confirming the Soviet identification. The Soviet team were not able to determine the cause of the crash, but hypothesized the pilot was flying low to evade radar and misjudged the aircraft's altitude. Judging from the fires that burned after the crash, the Soviets estimated the aircraft had enough fuel to fly to the Soviet cities of Irkutsk or Chita. All of the work and its results were kept secret from the public: outside of the investigative team, only KGB director Yuri Andropov and Soviet leader Leonid Brezhnev were informed. The report remained classified until the early 1990s, after the end of the Cold War.