James A. Gagliano is a CNN law enforcement analyst and a retired FBI supervisory special agent. He also serves as an adjunct assistant professor at St. John's University in Queens, New York. Follow him on Twitter: @JamesAGagliano . The views expressed in this commentary are his own.

(CNN) Seldom does a quiet, unassuming, and attention-eschewing career public servant like Robert Mueller, the current special prosecutor in the Russian election meddling investigation, command our attention enough to register on the Richter scale of relevance.

But here we are.

The ongoing heated debates over whether the investigation into possible collusive relationships between the Trump team and the Kremlin is akin to Watergate or the Salem witch trials present conflicting "certainties" and continue to fascinate us.

We have been inundated with innumerable essays that expertly argue whether Mueller has the goods on Trump, and whether or not he will elect to bring charges against the sitting President.

But instead, allow me to share some insight, from personal experience, on what might be motivating Mueller and just how we might distill what direction he may be heading in this critical closing stage of the investigation.

I served under four of the eight men to head the FBI. Mueller's 12-year tenure as director spanned almost half of my quarter-century career in the bureau.

And when former federal judge Louis J. Freeh became the FBI's fifth appointed director in September of 1993, I watched, fascinated, as he made it "Job One" to empty out the cubicles at FBI headquarters, reducing drastically the numbers of senior staff and returning these agents to the field as part of his plan to increase investigator ranks by shrinking FBI HQ.

Freeh even disbanded the director's personal security detail, preferring to have the Hostage Rescue Team (HRT) tend to his security needs during international travel.

7 days before 9/11

Mueller's arrival as Freeh's replacement occurred exactly seven days before 9/11. A week later, he was violently thrust into the unenviable position of guiding and reconstituting a reeling agency that was struggling to grasp just how and why the dots had gone unconnected.

He made immediate changes. He reshaped the FBI as less of a "criminal investigative agency" and more of an "intelligence gathering agency that worked criminal investigations."

The bureau's mission was sharply refocused on preventing the next terrorist attack on US soil. The bank robbers, kidnappers, Mafiosi, gangbangers, and Wall Street robber barons would still receive some deserved attention. But Robert Mueller privately seethed about the terrorist attack and swore that another 9/11 would not occur on his watch.

He succeeded. And he survived the critics in the Special Agent ranks -- including me -- who bristled at his realigning an agency that has stubbornly resisted change whenever it has been suggested or demanded over the course of its 110-year history.

Mueller also rebuilt FBI HQ, acknowledging that the FBI is a bureaucracy and should be staffed like one. Headquarters' ranks swelled. He reconstituted the director's personal security detail. This was less about his concern for his own safety -- hell, the man served in Vietnam with the 3rd Marine Division and earned a Bronze Star with "V" device for valor -- and more as a recognition of the new threat paradigm that global terrorism wrought.

JUST WATCHED Fox, GOP, Trump conspiratorial feedback loop Replay More Videos ... MUST WATCH Fox, GOP, Trump conspiratorial feedback loop 11:05

The new director then decided that promotions would also be inextricably attached to tours at headquarters. Some agents reveled in these policies. And some who took advantage of the new promotion requirements headed to DC, never to return to the field; Peter Strzok and Andrew McCabe, who are now the subject of criticism from President Trump and many Republicans, were just two such agents who embraced Mueller's vision.

While many agents groused about the changes, Mueller was implacable, withstanding the withering criticism, and holding the line. He was confident in his plans to realign the bureau's mission priorities, and needed a mechanism to compel participation from experienced -- or eager and ambitious -- investigators.

He never wavered

He was stern and taciturn; his approach never wavered. He patiently met with two personal friends of mine who headed the FBI Agents Association (FBIAA) in consecutive terms and politely acknowledged their recitations of rank and file grumblings.

He then flatly stated, as the conversations were later related to me, "Is there anything else? No? Good. Policy remains unchanged. Now, do your sworn duty and go back and advise our intrepid agent population that the American public, as always, is counting on them."

Meeting concluded.

Follow CNN Opinion Join us on Twitter and Facebook

In 2009, I headed a regional FBI office in upstate New York.

Receiving the unsettling news that a senior FBI executive and division head who was a personal friend of mine had been abruptly reassigned, I did the unthinkable.

In haste, I fired off a one-page email to the director of the FBI. This went against FBI protocols that date back to the J. Edgar Hoover era. FBI field supervisors don't ever correspond directly with the director.

Brave, or simply recklessly stupid, I prefaced my appeal by reminding him of the fact that I had served as one of his personal bodyguards on his first visit to Afghanistan to inspect the integration of agent investigators with their military counterparts in late 2003. I also referenced the times I had augmented his protective detail as a Senior Team Leader, with my FBI SWAT operators, on his numerous trips to New York City.

After vigorously defending my friend in the emailed appeal, I acknowledged that the director could certainly reassign me to the FBI's Butte, Montana outpost, which was J. Edgar Hoover's legendary reflexive reassignment "banishment" response to agents who erred or who simply earned his ire.

I braced myself for what I knew was deservedly headed my way.

The next day, though, I received the director's crisp two-line reply:

"JG, thank you for your input. No need to worry about Butte. RM"

The director's response, on a printed email exchange I've retained to this day, says everything you need to know about how Robert Mueller will handle the Russia investigation.

He will be fair. He will stand his ground. He won't suffer fools. He will respect a person's standing up on principle. If wrongdoing is discovered, he will bring the pain. And if there ultimately proves to be no "there" there, Robert Mueller will withstand whatever the shrill critics and armchair prosecutors toss his way as he makes the announcement.

I didn't always agree with Robert Mueller.

But I never doubted he would do the right thing.

And nor should you.