Patricia Dunn, 58, the former Hewlett-Packard chairwoman who authorized a boardroom surveillance probe that sullied her remarkable rise from investment bank typist to the corporate upper class, died Dec. 4 at her home in Orinda, Calif.

Her sister, Debbie Lammers, said Ms. Dunn’s ovarian cancer had returned.

Once one of the most powerful women in corporate America, Ms. Dunn saw her career tarnished in 2006 when she was ousted from HP and brought up on criminal charges, which were ultimately dropped. She had been accused of approving the company’s plan to snoop into the private phone records of board members, journalists and HP employees to ferret out the source of leaks to the media.

The scandal unfolded as Ms. Dunn battled a disease that had haunted her through a sparkling investment banking career and a stormy nine-year stretch on the board of HP, one of the world’s largest technology companies.

Ms. Dunn’s time at HP coincided with some of the most contentious and challenging periods since the Palo Alto-based company was founded in 1939.

In this Nov. 15, 2006 photo, former Hewlett-Packard Co. chairwoman Patricia Dunn sits in a courtroom in San Jose, Calif. Dunn died Dec. 4 at the age of 58. (PAUL SAKUMA/AP)

She joined HP’s board in 1998 and was instrumental in the hiring and firing of chief executive Carly Fiorina, whose flamboyant personality and ferocity in securing the $19 billion purchase of Compaq Computer ultimately helped hasten her ouster amid sagging stock prices and disappointing results from the combined company.

Ms. Dunn announced Fiorina’s ouster in February 2005 and named her successor, the low-key Mark Hurd, previously the chief executive of NCR. Hurd was ousted last year after an investigation into a sexual harassment claim found inconsistencies in expense reports.

Ms. Dunn also assumed Fiorina’s role as chairwoman at the time. She was forced out in September 2006 in an embarrassing scandal involving spying on the telephone records of board members, journalists and others.

A month later, California’s attorney general charged Ms. Dunn and four others with four felony counts each — conspiracy, fraud, identity theft and illegally using computer data — for their roles in the probe. That came two days before she started chemotherapy for advanced ovarian cancer.

The criminal charges against Ms. Dunn were eventually dropped, as prosecutors said she had little involvement in the “pretexting” — the ruse used by investigators to view private telephone records by pretending to be someone else — and because of her ailing health.

Charges against the other defendants were also dropped, with a judge calling their conduct “a betrayal of trust and honor” at worst that was not criminal behavior at the time it occurred.

Once an aspiring investigative reporter, Ms. Dunn, a graduate of the University of California at Berkeley, found more immediate and lucrative work in the financial world and made her mark in investment banking.

After working briefly as a part-time reporter for a community newspaper in San Francisco, she began her corporate climb by capitalizing on a temporary typist job that she landed at an investment firm in the 1970s.

She was able to turn the two-week typing assignment into full-time work and managed to rise through the ranks by earning a reputation as a hard-edged businesswoman. That reputation eventually helped her earn promotion to chief executive of fund-management behemoth Barclays Global Investors in 1995.

Ms. Dunn’s life had been far from charmed.

Financial difficulties dogged her family throughout her childhood, and her father, a vaudeville actor, died of a heart attack before she was a teen. Her mother later died of breast cancer.

It was at the height of Ms. Dunn’s corporate success when she became ill, forcing her to step down in 2002 from her role as Barclays chief to fight breast cancer and melanoma.

Two years later, doctors diagnosed ovarian cancer. In fall 2006, she underwent surgery for a metastasized tumor — three weeks before the public learned of the HP investigation that spawned congressional investigations and criminal probes and forced Ms. Dunn’s resignation.

As she and others involved in the probe grappled with the fallout, the public was given a rare view of the workings of a board consumed with bitter rivalries and dysfunction.

The probe Ms. Dunn authorized ultimately identified renowned physicist and former presidential adviser George Keyworth as the director who spoke anonymously to a technology news Web site about a confidential board retreat. Some viewed the article as innocuous. Venture capitalist Tom Perkins resigned from the board in protest over the investigators’ tactics.

Ms. Dunn worked on philanthropic matters in the years since the scandal, Lammers said. She and her husband endowed a faculty position at the University of California at San Francisco’s surgery department in honor of her mother.

Besides her sister, survivors include her husband, Bill Jahnke; three children, Janai Brengman, Michelle Cox and Michael Jahnke; 10 grandchildren; and a brother.

— Associated Press