The analyses of biographic publications, historical studies, and archival documents show that the majority of the OUN-B and UPA leaders and a very large proportion of members collaborated with Nazi Germany, mainly in the beginning of World War II. A significant percentage of the leaders and members of these organizations served in various police formations. They assisted the Nazi occupational authorities in implementing genocidal policies towards the Jews, Ukrainians, Russians, and Poles by helping to carry out mass executions and create conditions intended for the psychical annihilation of the entire Jewish population and significant numbers of Ukrainians, Russians, and Poles, specifically in Volhynia. The fact that many police commanders and large numbers of policemen in various locations and formations followed orders from the OUN-B by deserting en masse from their service, in particular in Volhynia in the spring of 1943, and forming the basis of the UPA shows that these commanders and police members were de facto controlled by the OUN-B.