US President Franklin Delano Roosevelt and his administration had credible evidence that it was the Soviets who committed the 1940 massacre of 22,000 Polish officers and inteligentsia in and near the Katyn Forest in Russia, but preferred to keep the information quiet, documents published last week suggest.

According to the documents, published by the US National Archives and Records Administration, the US received coded reports in 1943 from two of its officers who were taken by their German captors to the Katyn Forest to see mass graves packed with thousands of corpses in Polish officers’ uniforms.
The men reported that the corpses were in an advanced state of decay, proof that the killers could not have been the Nazis (as Soviet propaganda claimed), since they had only recently occupied the area.

It has long been suspected that President Roosevelt had known Soviet leader Joseph Stalin ordered the massacre, but didn’t want to alienate the USSR, an ally whom the Americans were counting on to help defeat Germany during World War II. However, documentation proving President Roosevelt’s knowledge of who was behind the crime had remained undisclosed until last week.

Though the messages did reach Washington, they disappeared soon after, indicating that the administration wanted to keep the reports under wraps. They failed to appear in a 1951-52 Congressional hearing on the massacre.

In response to the release, Foreign Minister Radosław Sikorski wrote in an open letter that “we must ensure that the fullness of the truth is uncovered for its own sake and in the name of historical justice.”

It was Soviet leader Mikhail Gorbachev who in 1990 finally admitted publicly that the USSR was responsible for the Katyn massacre.