Another team added to Sony's PSN investigation

Sony has added a third security firm to its PlayStation Network attack investigation, alongside US Homeland Security and the FBI.

Reuters reports Data Forte is the latest company to join the hunt, a private firm under the command of a former member of the U.S. Naval Criminal Investigative Service.

Earlier in the week, Sony listed Guidance Software and Protiviti as contributing to ongoing analysis of the attacks. Law firm Baker & McKenzie is also on board.

The FBI and US Homeland Security are also involved. Major credit companies are expected to conduct their own investigations, if they haven't already.

The PSN has been down for over two weeks following hacker activity and the compromise of user details, while Sony Online Entertainment has outed the suspected loss of thousands of stored credit card details. Australian and US congressional hearings have been called over the matter.