Washington (CNN) A watchdog review of how the FBI handled its investigation into then-presidential candidate Hillary Clinton is on track for release next March or April, Justice Department inspector general Michael Horowitz said Wednesday.

The inspector general gave no clues in Wednesday's appearance before the House oversight committee hinting at what the report would conclude. But he said the review is "moving along quite expeditiously."

Horowitz opened the probe in mid-January -- prior to President Donald Trump's inauguration -- when James Comey was still FBI director and when questions were still fresh about Clinton's use of a private email server as secretary of state.

Horowitz indicated at the time it would be a wide-ranging look at multiple ways the Justice Department and FBI may have impacted the election, including potentially improper disclosures of information and the bureau's decision, days before the election, to release documents on a controversial pardon issued nearly 16 years earlier by Clinton's husband, President Bill Clinton.

But no doubt central to the probe will be Comey's multiple announcements about Clinton's emails. In July 2016, he announced he would not recommend charges against Clinton. In late October -- less than two weeks before the election -- he notified Congress that the FBI obtained emails it previously did not have and would re-open the investigation.

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