He hovers over Washington´s seething political swamp like The Phantom. No one ever sees Robert Mueller, the special counsel leading the Russia collusion investigation; he never speaks.

But he´s constantly present, showing his hand through a trickle of court filings, each one stoking speculation through the halls of government, in offices and barrooms, and over dinner tables: What does he have on Donald Trump?

Eighteen months into his investigation, Mueller has the US capital spellbound.

He threw tantalizing new bait to Russia-gate adepts late Tuesday when he recommended to a court that Trump´s former national security advisor Michael Flynn, who had lied to investigators about his own Russia contacts, be let off without any jail time.

While Flynn was guilty of a “serious” offense, Mueller said in a court filing, he had fully cooperated with investigators in multiple cases, and submitted to interviews 19 times.

What Flynn told them, though, Mueller wasn´t saying.

It all adds to a mystique about the veteran prosecutor, who is depicted in fan memes as a Star Wars Jedi or a character from Game of Thrones. “Mueller is coming,” they warn ominously.

Liberals see Mueller as a warrior against injustice, and are whipped up by every court document containing a tidbit that potentially links the president to a crime.

Republicans are afraid to even imagine what damage their party faces from the outcome of the probe.

Trump, meanwhile, seems more on edge with each new court filing, blasting out tweets calling the probe an “illegal witch hunt.”