On 17 January 1945, during the Siege of Budapest by the Red Army, Wallenberg was detained by SMERSH on suspicion of espionage and subsequently disappeared. He was later reported to have died on 17 July 1947 while imprisoned in the Lubyanka, the prison at the headquarters of the KGB secret police in Moscow. The motives behind Wallenberg's arrest and imprisonment by the Soviet government, along with questions surrounding the circumstances of his death and his ties to US intelligence, remain mysterious and are the subject of continued speculation.