In his role as Gen. George Marshall 's assistant chief of staff for intelligence , he is known for having ordered the suppression of evidence that the Soviets were responsible for the Katyn massacre of Polish officers . While a prisoner of the Germans , U.S. Army Lieutenant Colonel John H. Van Vliet Jr. spent some time at the site of the Katyn Massacre , and concluded from what he saw that the Soviets were responsible for the atrocity . On May 22 , 1945 , immediately upon his arrival in Washington , D.C. , after being freed from captivity , Van Vliet filed a personal report with Bissell indicating what he had found . Bissell classified the report Top Secret in order to minimize its circulation , and later the report disappeared from archives
Katyn massacre
Katyn massacre
Clayton Lawrence Bissell