from wls-tv: A University of Chicago researcher died after being exposed to a strain of bacteria that causes plague. And Malcolm Casadaban's family wants answers. The Chicago Department of Public Health says there's no sign anyone else was exposed to the bacteria. The tragic irony is that Professor Casadaban had been trying to develop a vaccine so that thousands of people around the world wouldn't die a painful, ugly death from a bacterial infection related to the plague. But it was that bacterium that appears to have killed him.