A presidential committee tasked with investigating the illegal disclosure of classified government documents earlier this year has concluded that they may never know exactly what Edward Snowden took from the National Security Agency, according to a report by the New York Times.

It recently came to light that Snowden, the former NSA contractor who absconded with several secret documents extracted from the U.S. spy agency’s facility in Hawaii, was able to make off with an estimated 1.7 million NSA documents. Investigators know that roughly 200,000 of those documents were subsequently leaked to various people in the press, but are unsure where the remaining 1.5 million documents might be -- and whether Snowden still has access to them.

Six months into their investigation, authorities seem to have more questions than answers.  

“They’ve spent hundreds and hundreds of man-hours trying to reconstruct everything he has gotten, and they still don’t know all of what he took,” a senior administration official told the New York Times. “I know that seems crazy, but everything with this is crazy.”

Authorities said that Snowden, 30, who was granted permission from the Kremlin to live in Russia under asylum for one year, expertly covered his tracks when downloading government documents. According to the Times report, Snowden even used the passwords of other NSA employees to log in to classified systems, and hacked firewalls to enter restricted areas.

Snowden, whose leaks led to a series of global surveillance disclosures in the media, became both an enemy of the state and, at the same time, something of a national hero. Since the first documents were published in June of this year, the leaks have sparked a national debate in the U.S. about the overreach of government surveillance, with supporters of Snowden decrying the government’s use of warrantless wiretaps to spy on American citizens.

The leaked NSA documents revealed, among several startling revelations, that the government agency has the ability to tap into the telephone records of almost anyone it wants. Earlier this week, it came to light that the NSA even spied on players of two popular computer games, “World of Warcraft” and “Secondlife.”

The NSA justified its spying on online gaming communities by saying such groups could be “target-rich communication” networks.  

Snowden previously claimed that he does not have any copies of the stolen NSA documents after he turned the documents over to journalists. But investigators don’t think that’s the case, and are considering offering the former government contractor amnesty in exchange for those documents, according to CBS.

"So, my personal view is, yes, it's worth having a conversation about," Rick Ledgett, who is leading the Snowden leak task force, told CBS in an interview scheduled to air Sunday on "60 Minutes." "I would need assurances that the remainder of the data could be secured, and my bar for those assurances would be very high. It would be more than just an assertion on his part."