The power of DNA typing stems from the fact that in the nucleus of every one of the trillions of cells in a human being is a code that uniquely identifies that person, with the exception of identical twins. These genetic markers are inherited from a person's parents. The markers are the same whether they come from a person's saliva, blood, semen, skin, hair follicles, muscle tissue, or bones. In the analysis of DNA, the process called Polymerase Chain Reaction (PCR) can generate testable DNA even when samples are minimal or degraded. PCR is performed on regions of small repeating sequences called Short Tandem Repeats (STRs), resulting in thousands of identical copies of the DNA sample in a matter of hours. Through the DNA Identification Act of 1994, Congress created the DNA Advisory Board to develop rigorous quality assurance standards for the proficiency of forensic laboratories and forensic DNA analysts. This is intended to ensure that the DNA evidence presented in court is reliable. This article describes methods for collecting DNA evidence at the crime scene, as well as the nature of the training police officers should receive regarding the collection and processing of DNA evidence.