The CIA and FBI have set about the task of tracking down the person or persons responsible for giving top-secret surveillance methods to WikiLeaks.

At this point, it may be somewhat akin to looking for a needle in a haystack.

Said one report:

The leaker is believed to be an agency insider, CBS News reported, citing sources familiar with the probe. The manhunt is part of a joint agency investigation into a massive security breach that led to the release of thousands of documents by the website WikiLeaks.

Many of the documents were held in a highly-secure part of the CIA, meaning that the leaker would most likely have to be someone in the agency. But hundreds of agency employees and contractors are said to have had access to the documents.

Without giving away too much, WikiLeaks has suggested a former contractor with the agency gave them the information.

Last month, sources confirmed that the department was focusing its investigation on outside contractors.

When the leaks were first revealed, they were part of what WikiLeaks referred to as “Vault 7,” and gave details on how the CIA would hack into smartphones, smart TVs, and other such devices.

The agency has since said the information was outdated, and that they never used any such hacking methods on U.S. citizens.