A declassified Justice Department report has revealed that the NSA’s controversial e-mail surveillance program has been under the watchful eye of the FBI for several years.

The 231-page report, completed and classified in September 2012 by Justice Department’s inspector general Michael E. Horowitz, was recently made public in a semi-redacted form in response to a Freedom of Information Act request by The New York Times.

The report notes that the FBI became involved in 2008, gaining the ability to review e-mail accounts that the NSA wanted to target via its Prism program in an effort to make sure none of the accounts belonged to Americans.

A year later, in October 2009, the bureau began retaining copies of communications to analyze on its own time. And in April 2012, the FBI started nominating e-mail accounts and phone numbers of foreign individuals they wanted to keep tabs on.

Horowitz concluded that the bureau had done a good job in making sure that those targeted for surveillance weren’t American citizens.

It’s worth reiterating that some parts of the report are heavily redacted. For example, there was only a single mention of the NSA’s Prism program despite the fact that the program and many of its details were ultimately declassified following leaks from former government contractor and whistleblower Edward Snowden.