Here is one excerpt from their latest investigation:
It is possible that the conflict between the PRISM slides and the company spokesmen is the result of imprecision on the part of the NSA author. In another classified report obtained by The Post, the arrangement is described as allowing “collection managers [to send] content tasking instructions directly to equipment installed at company-controlled locations,” rather than directly to company servers.
Government officials and the document itself made clear that the NSA regarded the identities of its private partners as PRISM’s most sensitive secret, fearing that the companies would withdraw from the program if exposed. “98 percent of PRISM production is based on Yahoo, Google and Microsoft; we need to make sure we don’t harm these sources,” the briefing’s author wrote in his speaker’s notes.
An internal presentation of 41 briefing slides on PRISM, dated April 2013 and intended for senior analysts in the NSA’s Signals Intelligence Directorate, described the new tool as the most prolific contributor to the President’s Daily Brief, which cited PRISM data in 1,477 items last year. According to the slides and other supporting materials obtained by The Post, “NSA reporting increasingly relies on PRISM” as its leading source of raw material, accounting for nearly 1 in 7 intelligence reports.