In a sworn declaration, David Sherman, the NSA's associate director for policy and records, said the agency launched a "comprehensive" investigation after journalists began to write about top-secret NSA spy programs upon obtaining documents Snowden leaked to them. The investigation included searches of any records where emails Snowden sent raising concerns about NSA programs "would be expected to be found within the agency." Sherman, who has worked for the NSA since 1985, is a "original classification authority," which means he can classify documents as "top-secret" and process, review, and redact records the agency releases in response to Freedom of Information Act (FOIA) requests.
In his declaration, Sherman detailed steps he said agency officials took to track down any emails Snowden wrote that contained evidence he'd raised concerns inside the agency. Sherman said the NSA searched sent, received, deleted emails from Snowden's account and emails "obtained by restoring back-up tapes." He noted that NSA officials reviewed written reports and notes from interviews with "NSA affiliates" with whom the agency spoke during its investigation.