The Katyń massacre also known as Katyń Forest massacre, was a mass execution of Polish citizens ordered by Soviet authorities in 1940. Estimates of the numbers of executed persons ranges from 16.000 to 25.000 (The number of victims is estimated at about 22,000). Those who died at Katyń included an admiral, two generals, 24 colonels, 79 lieutenant colonels, 258 majors, 654 captains, 17 naval captains, 3.420 NCOs, 7 chaplains, 3 landowners, a prince, 43 officials, 85 privates and 131 refugees. Also among the dead were 20 university professors, 300 physicians, several hundred lawyers, teachers, priests, engineers and more than 100 writers and journalists as well as about 200 pilots. In all, the NKVD executed almost half the Polish officer corps. The killings were methodical. After the condemned’s personal information was checked, he was handcuffed and led to a cell insulated with a felt-lined door. After being taken into the cell the victim was immidiately shot in the back of the head. The Soviet Union claimed the victims had been murdered by the Nazis, and continued to deny responsibility for the massacres until 1990, when it officially acknowledged and condemned the perpetration of the killings by the NKVD, as well as the subsequent cover-up by the Soviet government.