Mirsky returned to Russia in September 1932. Five years later, during the Great Purge, Mirsky was arrested by the NKVD. Mirsky's arrest may have been caused by a chance meeting with his friend, the British historian E. H. Carr who was visiting the Soviet Union in 1937. Carr stumbled into Prince Mirsky on the streets of Leningrad (modern Saint Petersburg, Russia), and despite Prince Mirsky's best efforts to pretend not to know him, Carr persuaded his old friend to have lunch with him. Since this was at the height of the "Yezhovshchina", and any Soviet citizen who had any unauthorised contact with a foreigner was likely to be regarded as a spy, the NKVD arrested Mirsky as a British spy. He died in one of the gulag labour camps near Magadan in June 1939 and was buried on the 7th of that month. He was rehabilitated in 1962. Although his "magnum opus" was eventually published in Russia, Mirsky's reputation in his native country remains sparse.