Sony is bringing in the big guns to help it investigate the cyber attack that crippled the company’s networks almost a week ago. Reuters reports that Sony has brought aboard FireEye Inc.’s Mandiant forensics unit, an incident response firm that helps victims of security breaches identify the extent of attacks and restore systems. Meanwhile, according to the Financial Times, Sony has also approached the FBI for assistance.

Hackers from a group called Guardians of Peace paralyzed the computer systems at Sony Corp  last Monday, forcing computers on the internal network to display a red skull and the phrase “Hacked By #GOP,” which reportedly stands for Guardians of Peace. According to the Financial Times, the hackers also accessed confidential emails and other data, posted pictures online of Michael Lynton and Amy Pascal, Sony’s top entertainment executives, and left threatening messages.

Not long after the attack, online copies of DVD screeners of four unreleased Sony movies, including the upcoming Christmas release  “Annie,” as well as the Brad Pitt-starring, World War II flick, “Fury,”appeared on several movie-pirating websites. According to Variety, over 880,000 unique IP addresses have already downloaded the illicit copy of “Fury” since the leak. While the timing of the leaks is certainly suspicious, Sony is still searching for proof that the leaks are a result of the cyber attack, the Financial Times reports.

“The theft of Sony Pictures Entertainment content is a criminal matter, and we are working closely with law enforcement to address it,” a Sony spokeswoman said in a statement to Variety.