#It’s clear Robert Mueller was in no condition to run his investigation — so who did?

To the liberal media, special counsel Robert Mueller was the sharp, seasoned, no-nonsense prosecutor who would get to the bottom of “collusion.” But when Mueller testified before Congress on July 24, 2019, many were stunned to see a man struggling to answer basic questions.

Had his cognitive abilities declined during the probe?

The 76-year-old Mueller, members of President Trump’s defense team recalled, appeared to be a figurehead investigator, a man who seldom spoke or was even seen. On those rare occasions Trump’s lawyers had a chance to talk to the special counsel, Mueller’s aides appeared to be covering for his lapses in memory. So who was really in charge of the Mueller probe?

There were questions about Mueller’s mental condition even before he was appointed special counsel in May 2017. Chris Swecker spent 24 years in the FBI. He left the agency in 2006 with the highest respect for his old boss, with whom he had extensive daily contact for more than two years. “Mueller was super sharp,” Swecker remembered.

In fall 2016, working in North Carolina, Swecker invited Mueller to speak at a conference. Mueller flew from Washington, and Swecker met him for breakfast to brief him on the event. He noticed something he had never seen in his old boss. “I remember telling my wife after the breakfast that he’s slipping,” Swecker recalled. “You could tell the acuity was not there. . . . He was a little confused about what to do after he got off.” When Mueller was made special counsel the next year, Swecker wondered whether he was up to it.

Communications aide Mark Corallo was a Mueller fan even as he worked for the Trump defense team. After his departure in July 2017, Corallo awaited a call — not from his old colleagues, but from Mueller. Prosecutors wanted to question him about Trump’s role in drafting a statement in response to New York Times reporting on the now-infamous Trump Tower meeting.

The session with Mueller’s lawyers took place on Feb. 15, 2018. “At the end of the interview, Mueller came in and shook my hand and put his hand around my shoulder and said, ‘It’s good to see you,’ ” Corallo recalled. “He said, ‘I’m sorry you got dragged into this.’ When he left the room, I said to Andrew Goldstein, ‘Hey, how’s he doing?’ They said great. I said, ‘Well, he looks a little gaunt. Is he eating? Is he tired?’ They said, ‘No, he’s running circles around us.’ This was the first time I noticed that he was not physically robust.”

Nearly a year and a half later, watching Mueller testify on television, Corallo was taken aback. “When I saw him testifying, it was significantly more apparent,” he recalled. “And trust me, I was not the only one. Those of us who worked with Bob at the Justice Department after 9/11 and watched his testimony — the phone calls were flying. ‘Holy crap, what’s wrong with Bob? Is he sick?’ ”

In another key meeting, according to members of the Trump defense team, the special counsel seemed unfamiliar with a key Justice Department policy having to do with indicting a sitting president. “After that, we never met with Mueller, and we never spoke with him on the phone,” Trump defense lawyer Jane Raskin recalled.

“What’s galling to me in hindsight, knowing what we know, is that they dragged it out as long as they did,” said Corallo, the Trump comms man. “Which says to me that people other than Bob Mueller were running that investigation.”

But who? Speculation focused on Andrew Weissmann, the aggressive prosecutor sometimes known as Mueller’s “pit bull.” But the inner workings of the Mueller investigation were never fully clear to those outside. All the president’s lawyers could see was that Mueller didn’t seem to be in control.

“Bob at the end was AWOL,” Trump lawyer Jay Sekulow recalled. “That was the great con. He showed up for cameo appearances. He was the Wizard of Oz. He was back behind the big curtain, pulling some strings here and there, but when you pulled the curtain away, he wasn’t even really the one pulling the strings.”

When Mueller testified, everyone could see what Team Trump had seen. It wasn’t pretty. And it ended Democratic hopes of turning the Russia probe into a glorious victory.

Byron York is chief political correspondent for the Washington Examiner. This column was adapted from his newly released book, “Obsession: Inside the Washington Establishment’s Never-Ending War on Trump.”

Twitter: @ByronYork