On May 22, a man named Evgeny Freidman, the owner of more than 800 taxi licenses in New York City, pleaded guilty to "failure to remit to the New York State Department of Taxation and Finance $5 million in 50-cent [Metropolitan Transportation Authority] surcharges between 2012 and 2015," according to a press release from the state attorney general.

The guilty plea topped national newscasts and was discussed for days, which is a little unusual for a case in which a fairly small-time businessman — even one known around New York as the "taxi king" — admitted to pocketing a local tax on cab rides.

So why was it big news? Because Trump.

"More breaking news tonight," CNN reported May 22. "This, on President Trump's fixer, Michael Cohen. One of Cohen's business partners, a Russian immigrant known as the taxi king, has quietly agreed to assist federal investigators as part of a plea deal."

The idea was that, as part of his cooperation, Freidman would dish on Cohen, which would increase pressure on Cohen to dish on Trump with Trump-Russia special counsel Robert Mueller, and the end result would be … well, that was unspecified, but it clearly involved expectations of some sort of yet-to-be-exposed wrongdoing on the president's part.

Lest anyone forget, Mueller is authorized to investigate "any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump; and any matters that arose or may arise directly from the investigation," plus any obstruction of the probe. (A more detailed version of Mueller's assignment is still secret.)

Going after the taxi king in hopes of proving collusion in the 2016 presidential race is a bank shot, to say the least.

But other parts of Mueller's investigation — and certainly of the reporting on Mueller's investigation -- are bank shots, too.

This month a man named Jeffrey Yohai, who at one time was married to former Trump campaign chairman Paul Manafort's daughter, pleaded guilty to "conspiracy charges … relating to real-estate loans on properties in New York and California," as well as to misrepresenting his income to obtain an American Express "Black Card," according to the Wall Street Journal.

Yohai's case also topped some national newscasts. "Breaking news," CNN reported on May 17. "Paul Manafort's former son-in-law reaching a plea deal. What does this mean for Manafort and the Russia investigation?"

The idea was that, as part of his cooperation, Yohai would dish on Manafort, which would increase pressure on Manafort to plead guilty and dish on Trump, and the end result would be … well, that was unspecified, but it clearly involved expectations of some sort of yet-to-be-exposed wrongdoing on the president's part.

Another bank shot.

Even the case of Manafort himself, the highest-ranking Trump campaign official to be charged in the Russia investigation, is a bank shot. Manafort faces a long, multi-count indictment focusing on financial crimes he allegedly committed years before and apart from his work on the Trump campaign. The idea is to put so much pressure on Manafort with unrelated charges that he will eventually give up, plead guilty to lesser offenses, and dish on Trump.

That is what Rick Gates, Manafort's partner and the Trump campaign's deputy manager, has already done: pleaded guilty to crimes committed years before and apart from his work on the Trump campaign. Gates is now cooperating with Mueller, although it is not known what information, if any, he has provided about Trump.

The two other campaign figures who have pleaded guilty, Michael Flynn and George Papadopoulos, both admitted lying about Trump campaign-related matters, but not to any crime involving collusion, or conspiracy, or coordination, between the Trump campaign and Russia to fix the 2016 election.

Put it all together, and the impression left by the public parts of the Mueller probe is that Mueller has spent more than a year circling around the basic question of his investigation — Was there collusion? — but not answering it. He has liberally employed the prosecutor's technique of using unrelated charges to pressure targets in hopes of getting damning information on the real issue.

The only straight, direct charges are against a group of Russians who operated a content factory in the 2016 race. They're not expected ever to stand trial.

It should be said that all this is just the public part of the Mueller investigation. He might have some blockbuster charges in the works that no one outside his office knows about. Mueller has been consistently ahead of the reporting about his investigation.

But the fact that he has investigated and charged four figures from the Trump campaign — Manafort, Gates, Flynn, and Papadopoulos — and not charged any with crimes involving collusion appears to be significant. If there were in fact a Trump-Russia collusion scheme, they would likely have been involved. If not them, who?

So now prosecutors, and the press, are looking farther and farther afield — to the taxi king and beyond — in hopes of uncovering the collusion conspiracy they believe exists but so far can't find.