BOSTON, March 1 (Reuters) - Massachusetts U.S. Attorney Rachael Rollins has hired a former Justice Department inspector general to defend her in a widening ethics investigation into her appearance at a political fundraiser and her travel. The controversy has threatened to undermine Attorney General Merrick Garland’s vow to protect the Justice Department from partisan influence and efforts to extend progressive criminal justice policies championed by Rollins to the federal level. It is unclear what the inspector general's probe will find or when it will be completed. James Borghesani, a spokesman for Hayden, said they have received no inquiries from the inspector general's office. Investigators are also looking at Rollins' use of a personal cellphone, rather than her government-issued one, for Justice Department business, said two other people familiar with the matter.

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