The New York Times visits the FBI’s crime lab, an office tower 50 miles west of Washington where about 600 people process hundreds of thousands of pieces of evidence a year in specialized units for explosives, fingerprints, ballistics, toxicology and other forensic disciplines. Computers there contain the National DNA Index System, a database of 6.7 million genetic profiles, the world's largest repository of forensic DNA information. Under a 2005 federal law, the database will continue to include convicted felons, but it will also add genetic profiles of people who have been arrested but not convicted and of immigrant detainees – for an estimated 1.3 million more profiles by 2012.
But keeping pace with the expansion of DNA databases is a major challenge for the agency, which has sought ways to speed the processing of DNA evidence. As of 2007, the Justice Department estimated the backlog at 600,000 to 700,000 samples. In 2002, the F.B.I. was processing about 5,000 DNA samples each year. With the help of new robotic systems, analysts with the crime lab plan to process 90,000 samples each month by 2010.