From O. J. Simpson's "trial of the century" to the recent disappearance of Chandra Levy and the reopening of the Edward De Salvo case, the collection and use of DNA in criminal investigations has become a controversial and often confusing burden of proof. Blood Evidence explains the principles and science behind DNA testing and shows how it has both helped solve some of the most puzzling criminal cases in recent history and been used to discredit eyewitness accounts and physical evidence found at the crime scene. Written specifically for a lay audience, Blood Evidence is the first trade book to explore the complexities of DNA testing and the effect it has had on justice systems worldwide.