The U.S. House Committee on Energy and Commerce is compelling the testimony of Kevin Hunsaker, HP's chief ethics officer, and Anthony Gentilucci, the head of global investigations for HP, an aide for the panel said.
A number of other HP executives, includingand , are expected to appear voluntarily before the committee.
Ron DeLia, one of the private investigators hired by the technology giant to help gather information on board directors, company employees and, was also subpoenaed by the subcommittee, the aide said.
DeLia, who operates a Needham, Mass.-based company called Security Outsourcing Solutions, was invited to appear before the subcommittee, but he has indicated that he intends to seek protection under his Fifth Amendment right not to testify.
The congressional committee has been investigating "pretexting," the practice of obtaining private information through false pretenses, for seven months.
Hunsaker and Gentilucci are expected to leave their jobs at HP, sources have told CNET News.com
Besides the House panel, a number of other bodies are making inquiries into HP's investigation, including California's attorney general, the U.S. Securities and Exchange Commission, and the U.S. Department of Justice.