Conversation so far:
What was the accusation of Harry Dexter White?
Harry Dexter White was accused in 1948 of spying for the Soviet Union.
Was Whittaker Chamberse's accusations about Harry Dexter White found to be valid?
Chambers produced documents he had saved from his days as a courier for the Soviets' American spy-ring. The FBI Laboratory established that a memorandum was written in Harry Dexter White's handwriting.
Why did Whittaker Chambers warn officials about Harry Dexter White?
Whittaker Chambers became increasingly disturbed by Joseph Stalin's Great Purge, which began in 1936. He was also fearful for his own life.

Question: Did they take the warnings seriously?
Self-contained rewrite: Did officials take the warnings about Harry Dexter White seriously?