Advances in DNA technology over the last decade require police departments to take a new approach to how potentially critical evidence at a crime scene is located and identified. Cellular DNA, or “touch DNA,” as it is commonly referred to, is now routinely collected by many police agencies during the course of their investigations. Touch DNA consists of skin cells shed by a suspect during the commission of a crime on surfaces that were touched. It is now possible for investigators or scientists to collect cellular material at a crime scene and identify a suspect through subsequent DNA analysis.

The critical question, however, is how can evidence that is invisible to the naked eye be located and collected before the scene is released and the evidence is forever lost? The answer to that question is based on understanding the basic components of physical evidence; asking victims, witnesses, and suspects the right questions during an investigation; and sharing that information with crime scene investigators before the evidence is lost, diminished, or destroyed.