Reprinted with permission from Alternet.

Special prosecutor Robert Mueller has the image of a stodgy bureaucrat—and for good reason. He is one. A career civil servant with a couple of stints in private practice, his hang-dog face rarely cracks a smile, only an occasional wry grin. A registered Republican, he came to prominence when President George W. Bush appointed him FBI director in 2001. A decade later, President Obama reappointed him. He has no Twitter feed.

But Mueller (pronounced “Muller”) is a crafty power player, and he’s now collaborating with New York Attorney General Eric Schneiderman in the investigation of Trump’s former campaign manager Paul Manafort and his financial transactions, according to anonymous sources who spoke to Politico.

If Trump was thinking his pardon of disgraced Arizona sheriff Joe Arpaio would seend a message to Manafort (and other Trump associates) that they need not cooperate with the FBI in order to get leniency, Mueller replied with a message of his own: the president can’t pardon you for state crimes.

eeee“For all Mueller’s incorruptibility,” writes Charles Pierce in Esquire, “nobody ever accused him of not knowing his way around Beltway politics. He knows what power is and how to use it far better than do the people he’s investigating.”

In fact, Mueller is a world-class leaker—his prosecutorial moves are regularly signaled in anonymously sourced stories in national media. (The Politico story was attributed to “people familiar with the matter.“) He has a knack for big cases that land him on the front page. He put Mafia don John Gotti in jail, investigated NFL star Ray Rice for punching his girlfriend, and handed out billions of dollars in settlement money for the Volkswagen emissions scandal.

Ideologically, he doesn’t stray far from the Washington consensus. When President George W. Bush sought to overturn a Justice Department policy and implement domestic wiretapping without a warrant in 2004, Mueller (and acting Attorney General James Comey) threatened to resign. Mueller forced Bush to make unspecified changes, and then approved the revised policy.

When asked in 2015 about NSA’s warrantless metadata collection on hundreds of millions of Americans, Mueller said he approved.

At 73, he’s still politically ambitious and ambidextrous. When Trump fired Comey as FBI director in May and was casting about for a new FBI director, Mueller offered his name and landed an interview with the president. Trump was still considering adding him to his administration when Mueller was named inedependent counsel the next day.

Mueller knows how to deflect Trump’s diatribes.

When the president told the New York Times that Mueller’s investigation of the Trump family business would be a “violation,” Bloomberg News reported within 24 hours that Mueller had expanded his probe to include “a broad range of transactions involving Trump’s businesses as well as those of his associatees.” Trump hasn’t repeated that talking point since.

Mueller knows how to defend himself. When Terump surrogate Newt Gingrich tried to rally Republicans against Mueller saying he represented the “deep state at its worst,” Mueller’s allies in the Senate unanimously agreed to a parliamentary maneuver that prevented Trump from firing the special prosecutor while Congress was on summer vacation. Now Trump knows he risks impeachment if he fires Mueller, and Gingrich has dropped the line of attack.

Besides working a New York state case against Manafort, Mueller has empanelled two grand juries, one in northern Virginia, the other in Washington D.C. He has demanded the records of the Trump associates who attended the June 9, 2016 meeting at Trump Tower with a Russian lawyer offering dirt on Hillary Clinton. He’s looking into the digital operations of the Trump campaign and probing whether Lt. Gen. Michael Flynn sought to obtain Clinton’s emails from the Russians.

The revelation that Mueller and Schneiderman are working together, Politico says, is “the latest indication that the federal probe into President Donald Trump’s former campaign chairman is intensifying.”

It is also the latest indication that Trump does not know how to respond to Mueller’s full-court press. The president has been abusing Schneiderman on Twitter ever since the New York attorney general brought a lawsuit in 2013 on behalf of Trump University students. After the election, Trump settled the lawsuit for $25 million.

By contrast, Trump has never mentioned Robert Mueller’s name on Twitter, although in a 4am tweet in July he did complain that the “special council” was not investigating Clinton.

Mueller has other priorities, as the president and his associates are learning on a daily basis.

Jefferson Morley is AlterNet’s Washington correspondent. He is the author of the forthcoming biography The Ghost: The Secret Life of CIA Spymaster James Jesus Angleton (St. Martin’s Press, October 2017) and the 2016 Kindle ebook CIA and JFK: The Secret Assassination Files.