Институт красной профессуры
Not able to return to Romania, Leon settled in Moscow, adopting the pseudonym Adolf Cristin. Here he graduated in economics from the Institute of Red Professors in 1926, later becoming the head of the Industry Department of the Central Office of Economic Accounting of the USSR. At the request of the communists in Romania, he translated a part of Vladimir Lenin's works in Romanian, under the coordination of David Fabian. For a short time in 1928 he was a member in Political Bureau of the Central Committee of the Communist Party of Romania, along with fellow exiles Fabian and Elek Köblös.