DNA is the fundamental building block for an individual's entire genetic makeup. DNA is a powerful tool for law enforcement investigations because each person's DNA is different from that of every other individual. DNA can be extracted from a number of sources, such as hair, bone, teeth, saliva and blood. This book provides an overview of how DNA is used to investigate crimes and help protect the innocent. It also reviews current statutory law on collecting DNA samples, sharing DNA profiles and providing access to post-conviction DNA testing.