Over the past six months, the Justice Department has faced extraordinary tumult. And for each crisis, one figure with virtually zero public profile is always at hand, working behind the scenes: Dana Boente, one of only two Obama-appointed U.S. attorneys President Trump didn’t fire.

But this week, Boente’s role at the Justice Department will be more public than ever. The department is expected to announce that it has launched a wide-ranging investigation into government officials who may have illegally shared classified information with reporters. It’s a highly unusual move, as the department rarely, if ever, publicizes its investigations.

But these are highly unusual times. And no one is closer to all the action than Boente, who is temporarily helming the department’s powerful National Security Division.

As the department faces acid criticism from the president, Boente has quietly risen to its upper echelon, defending the travel ban when Sally Yates refused to and now gearing up for potential leak prosecutions. He’s an enigma to many: a quiet man who never married, never left the government, and apparently never stops working. And while he was President Barack Obama’s pick as U.S. Attorney for the Eastern District of Virginia, Trump opted to keep him in that role. If Trump follows through on his veiled threats to fire special counsel Robert Mueller, the Russia probe would likely, at least temporarily, become Boente’s responsibility.

Since April 28, Boente has run the National Security Division—responsible for prosecuting terrorists, hackers, Somali pirates, and others who pose security threats. The president still hasn’t named his official pick to run the National Security Division, though it’s expected to be Boeing assistant general counsel John Demers.

With the leak probe announcement expected this week, the division’s work seems be more political than ever. On July 25, the president tweeted that Attorney General Jeff Sessions is “VERY weak” on targeting leakers. The announcement will be viewed as a response to that criticism.

The investigation itself is Boente’s job. Carrie Cordero, formerly an attorney in the National Security Division, told The Daily Beast that these prosecutions are usually joint efforts between a U.S. attorney and the National Security Division.

Boente is the department’s top pinch-hitter. When Trump fired Sally Yates as acting attorney general for refusing to defend the travel ban, he stepped in and directed the department to defend it. While the Senate took weeks to confirm Rod Rosenstein as Sessions’ deputy, Boente was second in command there, overseeing the day-to-day work of the DOJ.

When Rosenstein went to Capitol Hill to meet with the powerful Senate Intelligence Committee chair and vice chair—a visit that came shortly after FBI director James Comey’s firing and drew significant media attention—Boente was along for the trip, as an ABC News video shows. And when James Comey told a Congressional panel that the FBI was investigating possible collusion between Team Trump and the Russians, Boente approved his statement, according a Yahoo News report.

Boente has never worked in private practice. He was born in a small town in central Illinois, and his father passed away when he was young, according to one of his longtime acquaintances. Ron Hosko, former deputy director of the FBI, said Boente spoke about his mother at length when he was installed as U.S. attorney on Feb. 26, 2016.

“He was so gracious, his comments were more about her than himself,” Hosko said. “Total class.”

After clerking for a federal judge in Illinois, Boente headed to the Criminal Section of the Justice Department’s Tax Division. He spent years in the tax division, and also served as acting U.S. Attorney for the Eastern District of Louisiana, and as acting U.S. Attorney for the Eastern District of Virginia before being confirmed unanimously by the Senate.

Boente never married and doesn’t have children. An associate said he normally works for 12 to 15 hours every day, sometimes from 7 a.m. to 9 p.m.

John Brownlee, a former U.S. attorney and acquaintance of Boente’s, said his enormous responsibility at the Justice Department didn’t surprise him.

“He’s someone that, across the board, people trust,” he said.

Boente may be best known for his work prosecuting former Virginia Gov. Bob McDonnell for corruption charges. Prosecutors ultimately dropped charges after the Supreme Court overturned his convictions because of overly broad directions given to jurors.

Hank Asbill, who was lead counsel for McDonnell during the prosecution, told The Daily Beast he’s known Boente for more than three decades, and that they’ve frequently on the opposite side of criminal cases in Virginia’s Eastern District.

“I knew and respected Dana as an adversary,” Asbill said.

Unlike some prosecutors, he added, Boente never seemed particularly outgoing or chummy to defense attorneys—perhaps because he had no aspirations of working with them.

“He’s quiet, he listens, I think he’s thoughtful,” Asbill said. “Dana’s close to the vest.”

While other prosecutors would sometimes be open with defense counsel about their reasoning for pressing or dropping charges, Asbill said Boente was never chatty.

David Rivkin, a former Justice Department during George H.W. Bush and Ronald Reagan’s administrations, said Boente’s decision never to enter the private sector is atypical. Most DOJ lawyers who have as much success as he does head to private firms, lured by lucrative salaries. But Boente never left.

“This is somebody who is a true public servant, who is interested in public service and for whatever reason does not care about making money,” Rivkin said.

Other former Justice Department officials took a different view of Boente’s lengthy government career. They told The Daily Beast that there’s a term for the type of person who stays in high-level DOJ jobs for so long: a survivor. Survivors are the opposites of Comey and Yates, who were fired for making controversial decisions. Survivors, meanwhile, draw criticism for avoiding hard decisions. Former DOJ officials, who didn’t want to criticize Boente on the record, said they were surprised and confused by his willingness to immediately defend the travel ban.

One former official said it looked like a tacit acceptance of the anti-Muslim animus that drove Trump’s birtherism. The travel ban is widely viewed as a watered-down version of the Muslim ban that Trump promised on the campaign trail. The former official expressed dismay that Boente, who was nominated to be U.S. attorney by President Obama, had willingly defended such an order. The perception among some former officials was that Boente was auditioning to keep his position as U.S. attorney. Whether or not that was his hope, it’s what’s happened: Boente didn’t just keep that role; he rose to an even higher post as temporary National Security Division chief.

“There’s no connection I know of that would lead anybody to believe that he’s a Trump guy and wouldn’t have been fired but for the circumstances that arose,” said a well-wired former department official, of Boente’s defense of the travel ban. “He solidified himself by doing what Trump wanted him to do.

“Everyone else got fired and he didn’t,” the former official added. “So it worked out for him.”

Boente isn’t the only high-level DOJ official to surprise his colleagues by advancing Trump’s priorities. When Rod Rosenstein was sworn in as deputy attorney general, Democrats lined up to praise him. But just weeks later, he drew blistering criticism for writing a memo that appeared to give the White House political cover for firing Comey—a move the president later said was because of the Russia investigation.

Former officials said Rosenstein is a survivor, in the same mold as Boente.

“He and Rod are both nice guys,” said a former official. “They are both company men for DOJ. If you want to understand how they tick, that’s the best way.”