An article from The Washington Post:

Federal authorities hope N-DEx will become what one called a "one-stop shop" enabling federal law enforcement, counterterrorism and intelligence analysts to automatically examine the enormous caches of local and state records for the first time.

[...]

The expanding police systems illustrate the prominent roles that private companies play in homeland security and counterterrorism efforts. They also underscore how the use of new data -- and data surveillance -- technology to fight crime and terrorism is evolving faster than the public's understanding or the laws intended to check government power and protect civil liberties, authorities said.

Three decades ago, Congress imposed limits on domestic intelligence activity after revelations that the FBI, Army, local police and others had misused their authority for years to build troves of personal dossiers and monitor political activists and other law-abiding Americans.

Since those reforms, police and federal authorities have observed a wall between law enforcement information-gathering, relating to crimes and prosecutions, and more open-ended intelligence that relates to national security and counterterrorism. That wall is fast eroding following the passage of laws expanding surveillance authorities, the push for information-sharing networks, and the expectation that local and state police will play larger roles as national security sentinels.

Law enforcement and federal security authorities said these developments, along with a new willingness by police to share information, hold out the promise of fulfilling post-Sept. 11, 2001, mandates to connect the dots and root out signs of threats before attacks can occur.