Curiously, the perpetrator had left a ransom note on "a 4GB USB stick...saved as a PDF file... a closer look at the USB drive turned up a couple of files that the criminal thought he'd deleted. One of them, a version of the ransom note written in Microsoft Word, contained metadata about the document's author, including his name: 'Paul P.'" Oops.

This was part of a trail of evidence leading to the arrest of Paul "Doug" Peters in the US state of Kentucky. As of this writing, authorities seek to extradite him to Australia to face kidnapping and breaking-and-entering charges.

So now you know that purging data from flash memory devices is even harder than you thought. Fortunately in this case, it helped lead to the capture of a suspect in a threatening incident. But it also shows that computer forensics can uncover information in unlikely situations, leading to real-world consequences. Computer security experts take note.