Any good lawyer will tell you that guessing the thoughts of jurors is a risky business, and that even old pros get it wrong all the time.

But David Wildstein, the star witness in the Bridgegate case, may have carved out an exception Monday.

He spent five hours on the stand describing himself as a career liar, a cheat, and a man so cravenly devoted to Gov. Chris Christie that he was willing to put school kids at risk to send a political message on the governor's behalf.

Several of the jurors looked to me like they had swallowed some bad clams.

Don't get me wrong: When it comes to the charges against the two defendants - Bill Baroni and Bridget Anne Kelly - I found Wildstein's testimony to be plausible.

But that's because it was supported by a mountain of emails, phone logs and text messages. Without that, every word out of this man's mouth shouts "reasonable doubt."

And that presents a dilemma for U.S. Attorney Paul Fishman. He faces the regular risk that he could lose the case, and allow one or both defendants to go free.

But he faces a second risk: He could become known as the guy who let the big fish get away.

It's unfair, if you ask me. His critics don't know what evidence he has on those bigger players, and they don't know what kind of deals he offered to get it.

But Wildstein is telling a larger story about the rotten underbelly of New Jersey politics. On the trial's opening day, prosecutors said he will testify that the governor knew all about the lane closures while the stunt was underway.

And on Monday, Wildstein added few other big pelts.

He said that Jersey City Mayor Steve Fulop promised to endorse Christie after the Port Authority did a favor for a private client that was paying Fulop on the side. Fulop won't say how much he was paid, or when he started and ended that side job. But he denies agreeing to endorse Christie.

Also on Monday, Wildstein accused Bill Stepien, then the governor's chief political operative, of being part of the conspiracy.

"I explained to Mr. Stepien that I was going to create the cover story of a traffic study," Wildstein testified.

And he said that Pat Schuber, a former Bergen County executive and now a member of the Port Authority board, was a Christie loyalist who was pulled into this cabal on Day One.

"Mr. Baroni was pleased that Mr. Schuber was in the loop," Wildstein said. Schuber later denied it.

But why isn't Fishman charging these other players, all of them fingered by his star witness? The answer must be that he lacks the kind of documentation he needs to support Wildstein's testimony.

Imagine if prosecutors charged the governor with taking part in this conspiracy on the basis of Wildstein's testimony alone. I'm not fan of Christie's, but I would not put him in jail on that evidence.

So what is Fishman to do? If he couldn't get the bigger players, should he have let Baroni and Kelly walk as well, given that they are clearly not the authors of this mischief?

That would be worse. Should prosecutors not charge mafia thugs unless they can also get the John Gotti of the operation?

You may wonder why prosecutors cut a deal for Wildstein, the chief architect of all this, while they work to put Baroni and Kelly behind bars. I don't know the answer, but my guess is Wildstein was smart enough to fold first. And the first suspect to break always gets a sweeter offer.

So Fishman doesn't get the big players, does that mean they all go free?

Absolutely not. This is a major test of the integrity and independence of the new attorney general, Chris Porrino. He now has solid evidence that the Port Authority and governor's office were used to promote Christie's re-election campaign. Will he act as a lawyer for the governor, or for the people of this state, as the Constitution demands?

Watch, too, for the Legislature to dive back in with vengeance once this trial is over. Listening intently at Monday's hearing were the co-chairs of the Legislative committee that exposed this scandal in the first place: Assemblyman John Wisniewski (D-Middlesex) and Sen. Loretta Weinberg (D-Bergen).

After the hearing Monday, both said Wildstein's testimony proved that Bridgegate was not a "rogue operation" but was a coordinated effort directed by the governor's office.

They have subpoena power, too. So no matter what happens in court, this thing ain't over, not by a long shot.

Tom Moran may be reached at tmoran@starledger.com or call (973) 836-4909. Follow him on Twitter @tomamoran. Find NJ.com Opinion on Facebook.