Because of that, Prica was arrested and sentenced to seven years in prison. In prison and afterwards, he translated classic Marxist books to Serbo-Croatian. After his release in 1937, Prica became one of the leading members of the newly formed League of Communists of Croatia. In March 1941, a few days before the Axis invasion of Yugoslavia, he was arrested together with a large number of Croatian left-wing intellectuals and was sent to Kerestinec camp, where Prica was handed over to the Ustaše authorities a few weeks later. He was shot as a retaliation for Partisan activity together with Zvonimir Richtmann, Božidar Adžija and Otokar Keršovani.