According to Todd Matthews from the National Missing and Unidentified Persons System, there are 90,000 people missing in the U.S. at any given time. Provide your readers with an in-depth look at the tools and techniques utilized by investigators of missing persons. Readers will discover how cutting edge forensic science reveals the clues in the tiniest bits of evidence. Sidebars offer descriptions of unusual cases, and historical crime-solving breakthroughs.