A knock at the door freezes all conversation. They come later. The only thing necessary for the triumph of evil is for good men to do nothing. It is not a stretch to compare Stalin's Purges and Hitler's Final Solution to the witch hunts in Europe 200 years ago. In a frenzy still unexplained, and largely unexplainable, at least 60,000 died.
Any outbreak seems quickly to become independent of the causes that trigger it.
Without proof, the denunciations became even more important. Encouraging denunciations helped draw additional people into the climate of paranoia. Denunciations were a sign of good citizenship. Being politically correct, you see, is nothing new. To dare doubt that the correct path was being followed, was supreme proof that you, yourself, were guilty of witchcraft, or treason.