The Letters That Left New Yorkers Terrified of the ‘Son of Sam’

New Yorkers are marking a grim milestone on Thursday: 40 years since the serial killer David "Son of Sam" Berkowitz was arrested for terrorizing the city with his signature .44-caliber revolver in a crime spree that ran between the summer of 1976 — also known as the "Summer of Sam" — and into 1977. It left six dead and seven wounded.