Paul Callan is a CNN legal analyst, a former New York homicide prosecutor and currently is "of counsel" to the New York law firm of Edelman and Edelman, PC, focusing on wrongful conviction and civil rights cases. Follow him @paulcallan . The views expressed in this commentary are his own.

(CNN) January is often a depressing month for people facing months of gray winter skies. Not so for FBI Director James Comey who sounded on Thursday like he was about to contort his 6'8" frame into a happy dance to celebrate Justice Department Inspector General Michael Horowitz's announcement that Comey, the FBI and the Justice Department will be investigated for their handling of the Hillary Clinton email investigation and other election-related issues.

Comey reacted to the announced probe by saying that he was "grateful to the Department of Justice IG for taking on this review" and further elaborated that "everyone will benefit from thoughtful evaluation and transparency regarding this matter." If Mr. Comey is grateful for an investigation by the Inspector General, he must have a fondness for root canals as well.

For those who may have forgotten the salient details of the Comey matter in the avalanche of other post-election controversies, the FBI Director found himself front and center in the presidential election when his putative boss, Attorney General Loretta Lynch engaged in an unscheduled airport meeting with former President Bill Clinton while the Department of Justice was investigating the matter of Hillary Clinton's email practices.

The Attorney General sought to restore public confidence in the investigation by ceding final decision-making power regarding it to Comey, placing the then widely-respected FBI director in the hottest of Washington hot seats.

In a foolish but undoubtedly sincere attempt to preserve the integrity of the FBI, he pushed his agents to wrap up the investigation, enabling him to issue what he described as an "unusual statement" containing more "detail" about the investigative process than is customary when investigations are closed. Comey noted that this was necessary because of the "intense public interest" in the case.

Last July, he told the nation that the FBI investigation of Secretary Clinton was now closed with no evidence of criminality having been found. He then tempered this exoneration with a series of devastating criticisms of the cavalier way classified documents were handled by the Clinton and her staff.

The former Secretary of State was accused of being "extremely careless" in the handling of highly classified material, a term of art perilously close to the concepts of "gross negligence " and "recklessness" often used in criminal indictments. Ultimately, however, Comey concluded that no reasonable prosecutor would bring criminal charges on the evidence at hand.

In his vain attempt to put the controversial investigation to bed, Comey had supplied both Democrats and Republicans with an arsenal of inflammatory campaign rhetoric which would simmer and then flare up throughout the campaign.

It got worse

Things only got worse when, 11 days before the election, the Director suggested that the investigation had to be reopened because a computer with possibly relevant information belonging to the controversial, Twitter-addicted husband of Clinton aide Huma Abedin had been discovered.

A few days later, just before the election, the FBI admitted that nothing relevant or incriminating had been found . Secretary Clinton was cleared again.

In the end Comey's decision to abandon the Department of Justice's sensible rule sharply limiting the issuance of interim announcements regarding ongoing investigations had disastrous results. Both the Trump and Clinton camps suspected a secret agenda focused on torpedoing their candidate while the public lost confidence in that once hallowed law enforcement institution, the FBI.

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Now, another investigation

Enter now the Department of Justice Inspector General, Michael Horowitz, to stir the still smoking embers of the Comey investigative fiasco with yet another investigation. The investigators will now be investigated. Horowitz, like Comey, is a former assistant US Attorney as well as a former Deputy Attorney General. (The Inspector General, many will be surprised to hear, heads up an office at the Department of Justice of over 400 employees. The Department of Justice law enforcement professionals are supposed to be honest individuals, sworn to fight the bad guys and protect the public. Why do we need 400 people watching them?)

How this will ultimately turn out is hard to predict with certainty. Though the Inspector General is empowered to recommend criminal charges, if warranted, such an outcome is highly unlikely on these facts. In the end a scathing report criticizing Comey's decision to go public with investigative details of the Clinton email scandal along with appropriate reprimands is the more likely outcome.

Donald Trump, upon assuming the presidency, will probably be looking to appoint his own FBI director rather than leaving the unpredictable James Comey in position to investigate the Trump Administration and/or Russian hacking and emails.

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While in theory, the new President Trump could defy recent presidential custom and practice to force the resignation of Inspector General Horowitz, such an act, though perfectly legal, would look too political and undermine Trump's quest to appear as the new honest, house-cleaning president. He sent a strong hint of his likely approach in forcing Republicans in Congress to back off on their ill-fated plan to eliminate the Congressional ethics monitoring system. The IG is a version of that committee in the executive branch, so keeping Horowitz in place would be a sensible approach.

A critical report by the IG could give President Trump sufficient ammunition to push Comey out of J. Edgar Hoover's historic seat. Although the FBI Director in theory serves a 10-year term (and Comey began his in 2013), it is hard to believe that he could survive the determined attack and opposition of the president he serves in the executive branch. Horowitz' report could give the president the "good cause" some legal experts believe he would need to terminate the FBI Director.

More likely the director would simply resign and secure a lucrative partnership at a prosperous private sector law firm rather than face a painful hearing process.

In the end, Comey's end run around the DOJ rulebook may have destroyed not only the presidential campaign of Hillary Clinton but also his own career and reputation. He has provided the co-author of "The Art of the Deal" with the leverage needed to push him off a political cliff and the ability to name a new, friendly FBI director to face the perilous years ahead.