Back in May 2011, 26-year-old James McCormick and 27-year-old James Marks were arrested after Sony alerted the U.K. law enforcement that many musical files had been swiped from their database.  The two young men hacked into the Sony computer systems and downloaded close to 8,000 files, which included artwork, videos and partial songs all in relation to the late Michael Jackson, and other Sony artists.  

According to Britain's Serious and Organized Crime Agency, some of the files stolen were "stems," which are tracks that can be used for mixes and dubbing other sounds on top of them, which lead authorities to believe that Marks and McCormick were attempting to sell these items.  They turned out to be right, after recovering chat logs from their computers that showed various evidence of them attempting to sell or trade certain files.

Sony has a seven year deal to sell up to $250 million worth of unreleased Michael Jackson recordings, so if Marks and McCormick had gotten away with this theft, it would've hurt Sony's pockets a bit.  They initially tried to pull the innocent card, but eventually pleaded guilty to two counts of "unauthorized access to computer material."

Source: huffingtonpost.com