A US government panel has asked an HP corporate ethics lawyer to testify in its 28 September hearing on the company's use of 'pretexting' to spy on journalists, board members and other employees.

The investigative unit of the US House Energy and Commerce Committee has asked HP senior counsel Kevin Hunsaker and Fred Adler, a company computer security investigator, to join a growing list of witnesses.

The subcommittee had also previously requested testimony from outgoing HP chairman Patricia Dunn, HP general counsel Ann Baskins, HP global security manager Anthony Gentilucci and outside lawyer Larry Sonsini, as well as outside investigators.

The practice of 'pretexting' usually involves pretending to be a person in order to obtain that person's personal information. An HP spokesman declined to comment.

Up until now, Dunn has insisted she merely initiated the probe of boardroom leaks, and was ignorant of specific techniques used by investigators.

"Unfortunately, the investigation, which was conducted with third parties, included certain inappropriate techniques. These went beyond what we understood them to be, and I apologise that they were employed," Dunn said in a recent statement.

But email correspondence examined by newspapers including The Wall Street Journal and The New York Times indicates that top HP officials solicited Dunn's opinion and questioned investigation techniques throughout the course of the leak probe.

As early as 6 August 2005, Anthony Gentilucci asked for Dunn's advice about using "internal and external sources" to gather intelligence on "interested parties", according to company email seen by the Journal. Gentilucci offered to brief HP management on more details of 'Project Kona' in a proposed meeting on 31 August. It's still unknown if that meeting took place, but Dunn replied to the email, promising to respond.

By 28 January 2006, email from Hunsaker to Adler shows that HP's own lawyers were closely questioning investigation techniques, according to the Journal. Asked whether HP could legally spy on board members' mobile-phone text messages, Adler replied: "Even if we could legally obtain the records, which we can't unless we pay the bill or get consent, I would highly suspect text-messaging records are not kept due to volume and expense."

It's unclear if HP obtained text messages. But in a 28 April email to Gentilucci and an outside investigator, Ron DeLia of Security Outsourcing Solutions, Hunsaker said he was writing at general counsel Baskins' request to confirm the details of how the investigation team obtained phone records, according to the Journal. In the email, Hunsaker described how investigators were making 'pretext calls'.

Hunsaker also said in the email that his legal research confirmed that pretexting is legal. However, California attorney general Bill Lockyer has said that using fraudulent means to obtain personal information is not legal in the state. Lockyer has said he has evidence to charge people outside and inside HP.

House investigators have also asked for testimony from DeLia and private investigator Joe Depante, owner of Action Research Group, which was reportedly hired by HP to help in the investigation.

Dunn agreed on 12 September to resign her own position, and will be replaced in January by current chief executive Mark Hurd.