Candy laced with cyanide and needles in marshmallows, we've long been warned to be suspicious of the sweet treats handed out by strangers at Halloween. But it seems that most stories of "Halloween sadism" are just that, stories. No child seems to have been  killed by adulterated Halloween candy... well... there is one terrible exception. The poisoned Pixy Stix of Pasadena, TX.

For a full list of sources used in this episode visit Tim Harford.com