Kammala wannan jumla: A watan Disamba na 1940, bayan farawar
A lokacin mamayar Soviet na Bessarabia da Arewacin Bukovina, Grünberg ya zama ɗan ƙasar Soviet, ya shiga NKVD, kuma an horar da shi azaman ɗan leƙen asiri a Chernivtsi (Cernăuți). An tura shi cikin sirri zuwa Romania a ranar 26 ga Mayu, 1941,