One of the most curious aspects of the U.S. government's case against MegaUpload is the large number of the company's internal communications acquired by the FBI.

Kim DotCom

(Credit: 3News in New Zealand)

In one exchange, MegaUpload managers fretted via Skype IM chat in 2007 that founder Kim Dotcom wasn't "safe with his money" and "the current situation is a bit risky," according to documents U.S. authorities filed with a New Zealand court this month as part of their criminal pursuit of the embattled cyberlocker service.

While it's still not clear how federal investigators gained access to the conversations of founder Kim DotCom and other top managers, there are hints that the FBI managed to place government-issued spyware on the defendants' computers.

The FBI cites alleged conversations between DotCom and his top lieutenants, including e-mail and Skype instant-messaging logs. Some of the records go back nearly five years, to MegaUpload's earliest days as a cyberlocker service–even though Skype says "IM history messages will be stored for a maximum of 30 days" and the criminal investigation didn't begin until a few months ago.

Sources told CNET yesterday that Skype, the Internet phone service now owned by Microsoft, was not asked by the feds to turn over information and was not served with legal process.

The U.S. Department of Justice told CNET that it obtained a judge's approval before securing the correspondence, which wouldn't have been necessary in the case of an informant. "Electronic evidence was obtained though search warrants, which are reviewed and approved by a U.S. court," a spokesman for the U.S. Attorney for the Eastern District of Virginia said.