Was “The Interview” the perfect cover? The Federal Bureau of Investigation conducted an extensive investigation into the recent massive Sony hack. Following the conclusion of that investigation, the FBI felt that its evidence pointing to hackers with ties to North Korea was so strong that President Obama publicly pinned responsibility on the Eastern nation.

Now, however, several security experts have come forward to suggest that North Korean hackers may only have partial responsibility, or perhaps they weren’t involved at all. Instead, it looks like the Sony hack may have been an inside job.

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“We are very confident that this was not an attack master-minded by North Korea and that insiders were key to the implementation of one of the most devastating attacks in history,” security expert Kurt Stammberger recently told CBS News. Stammberger is a senior vice president with cybersecurity firm Norse.

“Sony was not just hacked, this is a company that was essentially nuked from the inside,” Stammberger added.

Stammburger believes that a woman he refers to as “Lena” played a major role in the attack. He says that she was a former Sony employee who was with the company for 10 years before departing in May 2014.

“This woman was in precisely the right position and had the deep technical background she would need to locate the specific servers that were compromised,” Stammberger said. He believes her position within the company would have given her the knowledge and access needed to perpetrate the attack, and he says that most of the evidence pointing to North Korea is likely a case of misdirection.

“There are certainly North Korean fingerprints on this but when we run all those leads to ground they turn out to be decoys or red herrings,” Stammberger said.