Perhaps an apocryphal story, but one so good it should be told nonetheless.
Legend that has it that while giving a speech denouncing Stalin, Khrushchev was interrupted by heckler.
“You were a colleague of Stalin’s,” the man called out, “why didn’t you stop him then?”
“Who said that?” Krushchev shouted, unable to see who had spoken up.
The room went still; no one moved. After a few moments of silence, Krushchev said quietly “Now you know why I didn’t stop him.”