On 20 September 1944, Stahel was arrested by the NKVD together with Field Marshal Ion Antonescu. Interrogated on his part in the Warsaw Uprising, he was imprisoned in the Soviet Union. The exact date of his death is a subject of controversy. According to Soviet sources Stahel died on 30 November 1952, in Vladimir central transfer prison. However, other sources mention that Stahel died in 1955 in the Voikovo officer prison camp of a heart attack when he was informed of his possible transfer to Germany.