According to a report first published by the Wall Street Journal, Lauren Sanchez, the girlfriend of uber billionaire Jeff Bezos, reportedly sent the raunchy photos of Bezos and racy texts from the Amazon founder that were eventually leaked to the National Enquirer by her brother Michael Sanchez. Despite evidence from the recent federal probe, Sanchez has continued to deny that he sold the messages to the tabloid. 

The investigation into whether or not the National Enquirer (via their publisher American Media, Inc.) tried using the messages as blackmail. 

Source: cnn.com