Dunn has agreed to resign as chair in January after board meetings at the computer maker which took place over two days. She had previously insisted that she would only resign as chair if the board asked her to.
In a hunt for the source of press leaks Dunn authorised the use of private investigators. They then hired another firm which pretended to be board members, tricking phone providers into giving them access to personal phone call records.
When the actions became known in spring, venture capitalist Tom Perkins, a board member and friend of deceased company founders Bill Hewlett and David Packard, immediately resigned. The source of the leaks was identified as board member George Keyworth.
Dunn offered a qualified apology for her role in authorising the investigations in a statement. "The investigation, which was conducted with third parties, included certain inappropriate techniques. These went beyond what we understood them to be, and I apologize that they were employed," she said.
"I am taking action to ensure that inappropriate investigative techniques will not be employed again. They have no place in HP," said Mark Hurd, who is already chief executive and president of the firm and will take over as chair in January.
When news of the tactics became public last week, Dunn's and the investigators' actions became the focus of attention of the Justice Department, the Federal Bureau of Investigation and the attorney general in California, where HP is headquartered. That attorney general said that criminal charges may result from his investigations.
HP's shares rose slightly, by 20 cents to $36.56, on the news.
