A poster of Michael Jackson is covered with messages from fans. (Robyn Beck/AFP/GETTY IMAGES)

The Sunday Times reported (original link behind paywall) that 50,000 music files, including Jackson’s entire back catalog and some unreleased tracks, were allegedly compromised by hackers last spring. The breach was discovered shortly after April 2011, according to the paper, when Sony’s PlayStation Network was hacked and personal information from millions of users was taken.

Sony confirmed to the BBC that Jackson tracks had been stolen, but declined to say how many.

In 2010, the company reportedly agreed to pay the Jackson estate between $200 million and $250 million for the King of Pop’s back catalog and previously unheard material, according to Billboard. This collection is rumored to include Jackson duets with Queen lead singer Freddie Mercury and Will.i.am of the Black Eyed Peas.

View Photo Gallery: The star's father has refiled a wrongful death suit against the doctor charged in his son's death and added as a defendant a Las Vegas pharmacy. A look back at mourning of Jackson's death.

James Marks and James McCormick were arrested last May in connection with the Sony hacking. They appeared in court Friday where they denied the charges, according to Reuters. The men are expected to face trial in January.