Cameras, lasers and instrumentation help law-enforcement officers track down evidence and people in criminal investigations. Patrick Baxter, serving time in New York for car theft, was indicted last November on charges in three murder cases, one of them 13 years old. In August, Roy Criner was pardoned after serving a decade in a Texas jail for rape. In a recent New Mexico murder case, "invisible" evidence came to light. Photonics technology was behind each of these stories, adding more pages to a crime-fighting portfolio that includes finding evidence, identifying people and otherwise having helped solve criminal cases for decades...