A father-and-son private detective team, charged in a scheme by HP executives to spy on reporters, have entered pleas in federal court in San Jose — but a judge has sealed their pleas.

That’s according to CNET’s Michelle Meyers, one of the few reporters still covering the HP “pretexting” scandal which came to light in September 2006.

Meyers said it is unclear why U.S. District Judge D. Lowell Jensen of San Jose agreed to keep secret the pleas of Matthew and Joseph DePante of Florida, who were 32 and 64 respectively when they arraigned last November.

They’re charged with conspiracy to commit Social Security fraud by using the SSNs of reporters to gain access to their cellphone bills in a process called “pretexting.” Pretexting occurs when you assume the identity of another person in order to obtain that person’s personal information. HP used the cellphone bills to discover who was leaking confidential boardroom information to the media.

A former employee of the DePantes, Bryan Wagner, admitted to taking part in the spying campaign and pleaded guilty to charges of identity theft and conspiracy in 2007 in a plea bargain in which he agreed to testify against higher-ups in the case.

(If you’re following this story, the case number for the DePantes is CR-11-00821 and the Wagner case number is CR-07-00016.)