http://www.strategypage.com/htmw/htinte ... 10707.aspx
One of the more useful techniques used by the American military to build its database is biometrics. That is, every time the troops encounter a "person of interest", they don't just take their name and address, they also use portable electronic tools to take fingerprints, a retinal scan and photos. All this is stored in a database, which now contains hundreds of thousands of records for Iraqis, Afghans, and other "persons of interest". The fingerprints are particularly useful, because when they are stored electronically, you can search and find out immediately if the print you have just lifted from somewhere else, like the fragment of a car bomb, is in the database. The digital photos, from several angles, are also useful, because these pictures are run through software that creates a numeric ID that can be used by security cameras to look for someone specific, or for finding someone from a witness description. Other nations are digitizing their mug shots, and this enables these people to be quickly checked against those in the American database.
They discovered early on in Afghanistan, for example, that about one percent of the al Qaeda suspects they picked up, already had an arrest record back in the United States. It would be interesting to know what the percentage is in Pakistan.