Evidence suggested that Scarpa was involved in a personal relationship with his FBI handler, Lindley DeVecchio. DeVeccio, who was also a witness in a case connected to the Persico case. Weissmann had DeVecchio testify against Michael Sessa, a captain in the Colombo family, despite knowing DeVecchio was under investigation by the FBI for his relationship with Scarpa. Weissmann and his team failed disclose that to the courts and presented him as a solid witness in the case, according to Schoen and court documents.

More specifically, Weissmann withheld evidence to a court that would have helped the other side in a criminal case, which is required by law. In that previous case

A formal letter from U.S. Attorney Eastern District of New York Zachary Carter requested the judge to remove Weissman’s name, according to documents.

A formal letter from U.S. Attorney Eastern District of New York Zachary Carter requested the judge to remove Weissman’s name, according to documents.

In 1997 Andrew Weissmann was officially reprimanded by a judge in the Eastern District of New York for withholding evidence.

In 1997 Andrew Weissmann was officially reprimanded by a judge in the Eastern District of New York for withholding evidence.

One of Special Counsel Robert Mueller's lead attorneys has an ethics problem. Actually, a lot of ethics problems, considering what he's gotten away with. According to investigative journalist Sara Carter, Weissmann has been busted for withholding evidence in a previous court case involving prosecution of organized crime, to put an extra thumb on the scale of justice in his own favor. Carter writes that:

Mafiosos may not be a sympathetic bunch, but the law is the law and Weissmann didn't think it applied to him.

This, from a man gushingly portrayed in the New York Times last year as "fair."

No, actually, Weissmann doesn't really sound fair. According to the leftwing Daily Beast, in a piece published last August:

[Legal experts] believe [Weissmann's] presence on Mueller’s team means the probe may push legal boundaries as it investigates alleged collusion between Trump and Russian interests.

Then there was the Arthur Andersen case, which with Weissmann, shows a pattern of malfeasance. According to the Daily Beast:

During his years at the Justice Department, Weissmann built a reputation as a prosecutor willing to push the envelope – sometimes with disastrous results. He worked on the Justice Department’s Enron probe from 2002 to 2005. And while he was there, he helmed the prosecution of Arthur Andersen, Enron’s accounting firm, arguing that it had obstructed justice by destroying documents investigators would have needed. Weissmann and his team took the aggressive step of indicting the entire accounting firm. According to a source familiar with the case, the firm’s defense attorneys met with them [and asked Weissmann and his team] not to do so before the indictment, arguing that the firm would be certain to dissolve if it were indicted, leaving thousands of people jobless. “Their response indicated they didn’t care,” said the person familiar with the case.

Twenty thousand people lost their jobs over a junk case that was thrown out of court and this guy didn't care? Weissmann seems to have a history of dirty-cop tactics in his bid to make headlines, and it's particularly relevant in the current case with Robert Mueller since it now involves withheld evidence, the evidence that the phony Steele dossier, paid for by the Hillary Clinton campaign, and which the FBI knew was fake, was nevertheless the basis for a FISA warrant to spy on Trump advisor Carter Page, and with it, the entire Trump team, as Team Obama went wild with the unmaskings:

Now we have the weird recusal of Judge Rudolph Contreras in the case against former NSC Advisor Michael Flynn described by Clarice Feldman here. She writes:

The only reason I can imagine why Judge Contreras was recused – note: did not recuse himself – is that he was a member of the FISC, the court that grants surveillance warrants under FISA. As the evidence mounts that the warrant [to investigate Trump advisor Carter Page based on the tainted and phony contents of the Hillary Clinton campaign's Steele dossier] was improperly granted, someone – perhaps the chief judge of the district – removed him from further participation in the case, likely because Contreras approved the warrant and its extension. If the warrant was improperly issued, all the evidence it garnered is tainted. As to why the agreed upon delay, my thought is that Mueller wants to wait until the inspector general report so that, in a sense, his hands will be clean if the case is dropped, that he was compelled by the record to do so. I missed it earlier, but on December 12 of last year, Judge [Emmett] Sullivan issued a tough demand of the prosecution. They are compelled immediately to turn over all exculpatory material in their possession to General Flynn. The last paragraph of the order is particularly strong:

And here Weissmann has this history of not turning over exculpatory evidence to the extent that he has been blasted by other judges, even though the law tells him to do so. There's also Weissmann's willing to take down whole companies to get a collar as well. And according to the Daily Beast, there is Weissmann's crony closeness to Obama's lieutenants such as Obama Attorney General Loretta Lynch from his Brooklyn prosecutor days. Does this sound like someone who's fit for his job as dispassionate prosecutor in the nominally non-partisan Special Counsel's office?

It sounds as though Judge Sullivan is onto him and his dirty-cop prosecutorial games. Byron York has more on Sullivan here. If the case against Flynn is thrown out, it will be because of Robert Mueller's rather glaring dirty-cop problem, likely in Andrew Weissmann.