Barton Gellman and Ashkan Soltani, NSA tracking cellphone locations worldwide, Snowden documents show Washington Post (December 4, 2013):
The National Security Agency is gathering nearly 5 billion records a dayon the whereabouts of cellphones around the world, according to top-secret documents and interviews with U.S. intelligence officials, enabling the agency to track the movements of individuals — and map their relationships — in ways that would have been previously unimaginable.
The records feed a vast database that stores information about the locations of at least hundreds of millions of devices, according to the officials and the documents, which were provided by former NSA contractor Edward Snowden. New projects created to analyze that data have provided the intelligence community with what amounts to a mass surveillance tool.
Evidence marshaling software MarshalPlan