On 21 February 1946, under the supervision of the Commission of the SMERSH Counter-Intelligence Directorate of the 3rd Shock Army, the grave containing the corpses of Adolf Hitler, Eva Braun, as well as Joseph Goebbels, his wife, and children was uncovered. The grave was located on the territory of the Soviet military unit in Rathenow city. All of the corpses were in a half-decayed state in wooden crates.

The remains were transferred to Magdeburg, the location of the army’s SMERSH counter-intelligence unit, and were reburied in a pit two metres deep in the courtyard of house No 36 on Westendstrasse, by the southern stone wall of the courtyard. The grave was levelled to the ground “to give it the appearance of the surrounding area”.
The remains had previously been identified and were direct evidence of the death of those persons. The SMERSH Counter-Intelligence Directorate of the 3rd Shock Army was responsible for the safety of the remains. The reburial was carried out because the military unit was being transferred from Rathenow to Magdeburg.
Hitler and Braun committed suicide on 30 April 1945, Goebbels and his family on 1 May.
The boxes would remain in the ground until 1970, when the territory of the unit fell under the jurisdiction of the GDR. On 13 March 1970, Yuri Andropov, head of the KGB, ordered to destroy the remains. They were burned and the ashes scattered. A part of Hitler's skull and jaw were preserved as material evidence of his death and transferred to the KGB Archives in the USSR.
Sources:
Act of the 3rd Shock Army of the Soviet Occupation Forces in Germany from 21 February 1946. Electronic Library of Historical Documents