Several Russian zoologists after the October Revolution cast doubt on the veracity of records involving wolf-caused deaths. Prominent among them was zoologist Petr Aleksandrovich Manteifel, who initially regarded all cases as either fiction or the work of rabid animals. His writings were widely accepted among Russian zoological circles, though he subsequently changed his stance when he was tasked with heading a special commission after World War II investigating wolf attacks throughout the Soviet Union, which had increased during the war years. A report was presented in November 1947 describing numerous attacks, including ones perpetrated by apparently healthy animals, and gave recommendations on how to better defend against them. The Soviet authorities prevented the document from reaching both the public and those who would otherwise be assigned to deal with the problem. All mention of wolf attacks was subsequently censored.