On Wednesday, Jan. 29, 2003, police arrested 69-year-old Gerald F. Mason for the murder of two El Segundo, Calif., patrolmen. In 1957. The breakthrough came more than 45 years after the case was closed when, after receiving an anonymous tip, investigators ran fingerprints taken from the car they believed was the murderer\u2019s through the FBI\u2019s new national fingerprint database. The prints from the car matched a set of Mason\u2019s on file in South Carolina from when he served time in prison for burglary in 1956. On March 24 in Los Angeles, Mason pleaded guilty to the murders and was sentenced to two terms of life in prison.The database, which went live in July 1999, is the culmination of 10 years\u2019 work. However, says FBI spokesman Steve Fischer, the idea is much older. "The FBI has been creating a national fingerprint database of subjects arrested for criminal offenses since 1924," he says. But before 1999, this fingerprint library had been maintained only in hard copy form on fingerprint cards. That made national searches next to impossible. Now, searching a set of prints against the 45 million on file takes only a couple of minutes.The hands-on work for the $640 million database started in 1995, when the hard copy prints were converted into electronic images and then compressed to one-fifteenth their original size. Currently 40 terabytes of these compressed files are stored on CDs, and the system searches through them jukebox-style, spinning through disk after disk looking for a match. It\u2019s decade-old technology, but Fischer says it was the best bang for the buck when the project started. Of course, most law enforcement agents wouldn\u2019t care if a man behind a curtain was pulling levers as long as the database works. The application is so promising that Los Angeles has reopened 3,000 unsolved homicides. "The message is this," said El Segundo Mayor Michael Gordon after Mason\u2019s arrest. "If you commit a crime in this city?whether it\u2019s five days ago, five weeks ago, five months ago, or 45 years ago?we will not give up until you are brought to justice."