SS-Wachsturmbann Kurt Eimann shot about 2,000 Polish patients of the institutions in Konradstein, Schwetz and Riesenburg in the forest of Spengawsken from autumn 1939 to early 1940. Wachsturmbann Eimann also murdered up to 1,400 patients from Pomerania in the forest of Piaśnica by a shot in the neck (Genickschuss).

In November 1939, SS-Sondereinheit (Special Unit) Herbert Lange first killed psychiatric patients of the Owińska mental hospital with gas in the bunker of Fort VII in Poznań. This was followed by murders in mobile gas vans, which were later also used for other murders in Poland and Belarus. Sondereinheit Lange is responsible for the murder of more than 6,200 patients of institutions in Tiegenhof, Kościan, Kochanówka, Warta and Soldau.