HP chief exec Mark Hurd has called the spying scandal that has swamped the company a "rogue investigation," in an advance copy of testimony he will give to a Congressional hearing later today.

"How did such an abuse of privacy occur in a company renowned for its privacy? The end came to justify the means," Hurd wrote. "The investigation team became so focused on finding the source of the leaks that they lost sight of the privacy of reporters and others. They lost sight of the values HP has always represented."

The release of the testimony is a clear effort on Hurd's part to distance himself from the scandal which engulfed former chairman Patricia Dunn, who was forced to resign last week, and threatened to pull him in too when it was revealed he knew more about the investigation that he had previously made clear.

Dunn meanwhile defended her decision to investigate the leaks of confidential board discussions to the news media. "I wish fervently that none of this had ever happened," she has said in her testimony, also released early. "But boards have an unquestionable obligation to take steps to prevent [leaks]. That certain steps taken during the investigation went well beyond what was appropriate does not undermine the importance of the board's mission in this matter."

Both Hurd and Dunn are among several witnesses expected at a hearing before the Oversight and Investigations Subcommittee of the House Energy and Commerce Committee today in Washington. The committee is looking into the practice of "pretexting," or using false pretenses to gain access to confidential records. Investigators hired by HP to find the source of leaks engaged in pretexting to get hold of the phone records of directors, HP employees and reporters who cover the technology company.

Although much of the criticism of the scandal surrounds the tactics used by the investigators, Dunn wrote in her testimony that equal consideration should be given to the leaks from within the company that damaged HP. HP board leaks to the media made it difficult for the board to deal with important issues candidly, she has argued.