Smelling a rat in a bag of chips

CHICAGO — Some crime scenes are exactly the size of a breadbox.  

Every year forensic scientist Brendan Nytes sees a few cases where a dead rat or mouse is found in box of cereal, a jug of vinegar or a loaf of marble rye. His job is to distinguish genuine contamination from the surprising number of cases involving the intentional introduction of a dead rodent to a perfectly wholesome food product.