Attorney General Bill Lockyer filed criminal complaints in Santa Clara County Superior Court naming Dunn, ousted HP chief ethics officer Kevin Hunsaker, private investigator Ronald DeLia, and outside investigators Joseph DePante of Melbourne, Fla. and Bryan Wagner of Littleton, Colo.
They each face four felony charges: use of false or fraudulent pretenses to obtain confidential information from a public utility; unauthorized access to computer data; identity theft; and conspiracy to commit each of those crimes.
HP CEO Mark Hurd is not among those charged, nor was HP's former general counsel Ann Baskins, who had some oversight of the company's investigation of media leaks.
Three of the five charged were likely hired to carry out spy activities, CBS Radio News correspondent Steve Futterman reports.
The scandal erupted last month when HP disclosed that detectives it hired to root out a series of boardroom leaks secretly obtained detailed phone logs of directors, employees and journalists. The detectives used a potentially criminal form of subterfuge known as pretexting to masquerade as their targets and trick telephone companies into turning over the records.
Dunn, who initiated the investigation, said she didn't know until after the fact that the detectives went to such extremes to unearth clues about the leaker's identity. She resigned from HP's board last month amid the uproar over the spying campaign, which has also prompted the resignation of two other board members.
Dunn, 53, who has survived breast cancer and melanoma, will begin chemotherapy treatments for advanced ovarian cancer on Friday at the University of California, San Francisco, according to a person close to Dunn who asked to remain anonymous because a formal announcement wasn't planned.
Lawyers for Dunn and the others charged did not return calls seeking comment. HP did not immediately comment, nor did a spokesman for Lockyer.
Hunsaker, who directed the investigation, left the company on Sept. 26; DeLia runs a Boston-area detective firm called Security Outsourcing Solutions, a longtime HP contractor commissioned to conduct the leak probe.
DeLia in turn hired DePante's company to gather information, and DePante hired Wagner to obtain the private phone records of HP directors and journalists.
HP eventually identified director George Keyworth II as the source of a leak to a Cnet Networks Inc. reporter. Keyworth resigned after the scandal went public in early September.
Another director, venture capitalist Thomas J. Perkins, resigned from the board in May after learning about the tactics used by HP's investigators. He then pressured the company to publicly disclose the reason for his departure, leading to the regulatory filing that revealed the investigators' use of pretexting.
The FBI and a congressional panel are also looking into the HP pretexting scandal. Dunn testified last week before the panel, saying she didn't know about any potentially illegal tactics used in the investigation and wasn't responsible for the probe.