Professor Wendy Lower from Towson University wrote that although Ukrainians greatly outnumbered other non-Germans in the auxiliary police, only the ethnically German Volksdeutsche from Ukraine were given the leadership roles.[12] Many of those who joined the ranks of the police had served as militiamen under Soviet rule since the invasion of Poland in 1939.[13] Professor Tadeusz Piotrowski wrote that the majority of Ukrainische Hilfspolizei in Galicia came from OUN-B,[14] which was confirmed by Professor John-Paul Himka as an important transitional stage of OUN involvement in the Holocaust.[15] According to Andrew Gregorovich, the ethnic composition of Auxiliary Police reflected the demographics of the land and included not only Ukrainians but also Russians from among the Soviet POWs, Poles drafted from the local population, and German Volksdeutsche of all nationalities.[16] However, Browning (Ordinary Men) and Lower both insist that, for the German administration, nobody but the "Ukrainians and local ethnic Germans could be relied upon to assist with the killing".[17][18] Also, according to Aleksandr Prusin most members were ethnically Ukrainian, hence the name or the force.[19] The auxiliary police were directly under the command of the Germanic-SS, the Einsatzgruppen, and military administration.[20]