On the afternoon of Jan. 26, 1948, a man claiming to be a public health official walked into a branch of Teikoku Ginko (Imperial Bank) in Tokyo's Shiinamachi district and told all 16 people present that dysentery had broken out in the neighborhood.

After handing bank clerks a business card that identified him as an epidemiologist, the man told everyone present to drink a few drops of liquid he claimed was a remedy. The liquid, however, was actually poison.

Twelve of the 16 people died, and the man escaped with cash and checks worth ¥160,000.