Matthew Whitaker, whose brief tenure as acting U.S. attorney general was marred by accusations he might try to interfere in a probe of President Donald Trump's campaign, left his Justice Department job over the weekend, a department spokeswoman confirmed on Monday.Whitaker's last day at the department was on Saturday, the spokeswoman said, adding she did not know where he might be headed next.In mid-February, Attorney General William Barr was sworn in and Whitaker stepped down from the top post to become a senior counselor in the office of the associate attorney general. In one of his final acts as acting attorney general, Whitaker testified before the House Judiciary Committee, where combative Democratic lawmakers pressed him on whether he had tried to interfere with Special Counsel Robert Mueller's investigation into whether Trump's campaign colluded with Russia.Whitaker denied any interference and said he had not talked to Trump about the probe. Trump has denied colluding with Russia and has repeatedly called Mueller's investigation a "witch hunt."Whitaker first joined the Justice Department as former Attorney General Jeff Sessions' chief of staff in the autumn of 2017. Trump handpicked him as acting attorney general in November after the president ousted Sessions.Whitaker's appointment alarmed Democrats, who pointed to numerous negative comments he had made about the probe during his previous work as a conservative political pundit.Those concerns were exacerbated after the Justice Department disclosed that its career ethics lawyers had recommended that Whitaker recuse himself from the probe to avoid the appearance of a conflict but that he declined to do so.The Justice Department also faced a backlash in the form of multiple lawsuits alleging Whitaker's appointment violated the U.S. Constitution and the federal law governing succession at the department.None of the plaintiffs who challenged Whitaker's appointment prevailed, and the issue has since been mooted with Barr's Senate confirmation.Although Whitaker is no longer with the Justice Department, he could still find himself in the spotlight.Following his contentious House of Representatives testimony last month, Democrats have raised questions about whether he had been truthful in his statements under oath. In a letter to Whitaker, the panel's chairman, Jerrold Nadler, said he wanted Whitaker to come back and follow up on answers he gave that seemed "unsatisfactory, incomplete or contradicted by other evidence." Nadler told MSNBC that Whitaker has agreed to testify again before the committee and his appearance would happen in the next few weeks.