[1] A member of the local Jewish community, he fought in the Romanian Army in World War I until 1917, when he deserted.
He fled to Odessa, where, together with Christian Rakovsky and Mihail Gheorghiu Bujor, he took part in a revolutionary battalion for Romanian troops.
Later, as a courier employed by Soviet Russia, Marcovici entered Romania a number of times, bringing in printing presses and important sums of money in order to finance the communist factions within the Socialist Party of Romania, as well as Bolshevik-inspired terrorist groups.
[3] Becoming involved with the banned Romanian Communist Party (PCdR), Marcovici joined its secretariat and was chief of the central committee's technical operations, organizing networks and clandestine links.
He played a similar role within the International Red Aid, supervising assistance in the form of money, food, clothing and newspapers sent to prisons.