Washington (CNN) One of Defense Secretary James Mattis' most senior civilian advisers is being investigated by the Defense Department Office of Inspector General for allegedly retaliating against staff members after she used some of them to conduct her personal errands and business matters, according to four sources familiar with the probe.

Dana White, the Trump administration political appointee who serves as the Pentagon's chief spokeswoman, has been under investigation for several weeks after multiple complaints were filed against her.

White is alleged to have misused support staff, asking them, among other things, to fetch her drycleaning, run to the pharmacy for her and work on her mortgage paperwork. Staffers also charge that she inappropriately transferred personnel after they filed complaints about her.

White has not been found in violation of any federal regulation or policy at this point. The inspector general's office declined to comment.

As many as half a dozen defense personnel, and possibly more, have been interviewed, the sources say. All the officials CNN spoke to asked that their names be withheld, not just because the investigation remains ongoing, but because of concerns about reprisal.

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