The FBI thinks it's found the person who leaked top secret intelligence about Russia

AP Photo/Alexander Zemlianichenko, pool

Russian President Vladimir Putin gestures while speaking to the media after the Belt and Road Forum at the China National Convention Center at the Yanqi Lake venue outskirt of Beijing in China, Monday, May 15, 2017.

NBC News confirmed Monday that 25-year-old Reality Leigh Winner was arrested on charges involving the leak of a top-secret National Security Agency document to The Intercept that detailed a Russian hacking operation targeting US voting systems.

Winner worked for a company called Pluribus International Corporation, the Justice Department said. The company's clients include the Defense Intelligence Agency, US Army, and US Central Command.

The FBI special agent who wrote the affidavit in support of Winner's arrest alleges that she printed out the document from her work computer on May 9, 2017, and mailed it to a "News Outlet." The outlet then showed the document to the NSA -referred to as "the Government Agency" - in order to confirm its authenticity.

"The U.S. Government Agency examined the document shared by the News Outlet and determined the pages of the intelligence reporting appeared to be folded and/or creased, suggesting they had been printed and hand-carried out of a secured space," the agent, Justin Garrick, wrote.

"The Government Agency conducted an internal audit to determine who accessed the intelligence reporting since its publication," he wrote. "The U.S. Government Agency determined that six individuals printed this reporting. WINNER was one of these six individuals. A further audit of the six individuals' desk computers revealed that WINNER had e-mail contact with the News Outlet. The audit did not reveal that any of the other individuals had e-mail contact with the News Outlet."

Winner "admitted intentionally identifying and printing the classified intelligence reporting at issue" and mailing it to the outlet, according to the affidavit.

One additional clue that points toward the NSA document as what Winner leaked is that it has a declassification date of 05/05/2042. The affidavit says that the leaked top-secret document was first published "on or about May 5, 2017."

The Intercept did not immediately respond to a request for comment.