In 1941, after the Axis attack on the Soviet Union, Panet was part of a group tasked by the Romanian Communist Party to prepare explosive material for use in sabotage actions against German troops stationed in Romania. The group, which also included Panet's wife, Lili, Ada Marinescu, dr. Adalbert Kornhauser and Elisabeta Naghi, organized a laboratory in the bathroom of Panet's house in Bucharest. In October, the Panets were arrested by the Siguranţa Statului (Romania's secret police) and all explosives were confiscated.