FBI Director James Comey revealed a new review of recently-discovered emails related to the FBI's previously-closed investigation into Hillary Clinton's use of a private server.

“I must be out of my mind to be following Bob Mueller,’’ Comey said in the 2013 White House Rose Garden ceremony.

"I don't know if I can fill those shoes, but I know that, however I do, I will be standing truly on the shoulders of a giant."

Indeed, Mueller’s tenure was widely credited with the post-9/11 transformation of the FBI from a largely reactive law enforcement institution to an intelligence-driven agency bent on preventing new terror strikes.

And he did it by shunning the spotlight at virtually every opportunity.

By contrast, Comey, 55,  has staked out a public profile that couldn’t be more different than his predecessor and the traditional confines of the office itself.

He has bluntly acknowledged law enforcement’s fraught relationship with racial and ethnic communities in addresses at Georgetown University and Birmingham, Ala.,and has suggested that less-aggressive policing may be contributing to troubling spikes in violent crime in some parts of the country — a position that has put him at odds with his boss, Attorney General Loretta Lynch, and even the White House.

He has drawn the wrath of the tech industry and privacy advocates earlier this year as the face of the government's legal battle with Apple Inc. 

to gain access to the iPhone of San Bernardino terrorist Syed Farook. The high-stakes dispute represented what Comey described as the  “hardest problem I’ve encountered in my entire government career.’’

And he has publicly faced new questions about the bureau's capacity to confront an increasingly daunting challenge: thwarting violent extremists from within who are drawing inspiration from a constellation of radical ideologies to commit mass murder.

  At one point during a briefing last week on the Orlando massacre, carried out by a gunman who was twice before on the FBI's radar, Comey acknowledged the vexing nature of the mounting burden, ticking off a list of recent bloody assaults and attempted attacks that have scarred Garland, Texas, Charleston, S.C., Chattanooga, Tenn., San Bernardino, Calif. and now Orlando.

"We are looking for needles in a nation-wide haystack,'' Comey said, "and we are also called upon to figure out which pieces of hay may some day become needles.''