The Central Intelligence Agency played a crucial role in helping the Justice Department develop technology that scans data from thousands of U.S. cellphones, part of a little-known high-tech alliance between the spy agency and domestic law enforcement, according to people familiar with the work.
The WSJ reported last year [wsj.com] on how the Justice Department flew low-flying light aircraft over US towns and cities in an effort to hunt suspected criminals. In the process, a significant number of Americans' data is scooped up. The CIA is not allowed to conduct most of its operations on US soil so this cooperative effort demonstrates how criminal investigations rely on technical and operational support [zdnet.com] from intelligence agencies.