Soon after the House Judiciary and Intelligence Committees announced that Robert Mueller had agreed to testify on July 17, 2019, news broke that following the public questioning of the former special counsel, committee members would quiz Mueller’s staff in private. “There’s time also allotted for executive session after Mueller testifies,” House Intelligence Committee Chairman Adam Schiff told CNN, “that will be with his staff.”

Some on the right have suggested that this closed-door session will inflict more harm on the president than Mueller’s public testimony. Former U.S. attorney turned criminal defense attorney and special counsel critic Joe diGenova told Fox News host Lou Dobbs that “the real damage is going to be done the next day when they have testimony from Weissmann and his aides, which will be done in executive session with unlimited questioning.”

“That’s when the damage to the president is going to be done,” diGenova added, calling Mueller “nothing more than a figurehead.” “This has always been the Weissmann investigation, and it’ll be the Weissmann testimony,” diGenova said, referring to Andrew Weissmann, the lead attorney dubbed Mueller’s “pit bull.”

No doubt Democrats in the House sought Mueller’s testimony, and that of his staff, for one reason only: to paint Trump as a criminal without the politically risky business of impeachment. And I have no quibble with the contention that Weissmann held the reins of the special counsel probe and that Mueller’s former top lawyer will try to vilify the president.

But, far from damaging Trump, Weissmann’s closed-door testimony—if handled properly—will assist Republicans in unraveling the Russia-collusion-turned-obstruction witch hunt and inflict far greater damage on the Democrats. Here’s why.

While the general populace viewed Mueller as an apolitical straight-shooter (at least until he put his name to a final report that exposed him as a political hack), those familiar with Weissmann’s prosecutorial and professional history held a much different view of the number two man. Yet, even now, only a small segment of society knows Weissmann’s name, much less the details about his questionable background. That will change soon with Democrats’ decision to call Weissmann to testify, thrusting Mueller’s sidekick into the spotlight—blemishes and all.

And Weissmann’s warts are many. First, we have Weissmann’s applause for the insubordination former acting attorney general Sally Yates showed President Trump. “I am so proud. And in awe. Thank you so much. All my deepest respects,” Weissmann emailed Yates upon learning that Yates had refused to fulfill her duty to defend Trump’s travel ban and had instructed Department of Justice attorneys to do likewise. Trump immediately fired Yates, while Mueller later chose Weissmann to lead the special counsel team.

We also have Weissmann’s financial support of the Democratic National Committee and Hillary Clinton through thousands in campaign contributions. The Wall Street Journal also reported that Weissmann attended Clinton’s 2016 election night party in New York City, further raising the specter of an anti-Trump bias at play.

Then there are questions concerning Weissmann’s meeting with Associated Press reporters on April 11, 2017, about Trump’s onetime campaign chair, Paul Manafort. The following day, the AP published an “explosive expose,” detailing Manafort’s purported dealings with Ukrainian officials, including approximately $1.2 million in payments recorded in a handwritten ledger in Ukraine, suggesting Weissmann had leaked details to the journalists during the April meeting.

Weissmann’s meeting with the AP reporters pre-dated the special counsel investigation, as did Weissmann’s knowledge of the Steele dossier and author Christopher Steele and Fusion GPS Founder Glenn Simpson’s meetings with DOJ lawyer Bruce Ohr. Yet many in the media have ignored Weissmann’s early involvement in the investigation into the Trump campaign—even after Ohr’s reveal in his congressional testimony that, in fall 2016, he shared with Weissmann information peddled by Steele and Simpson. This fact suggests Weissmann knew that the FBI was using Ohr as a conduit for Steele’s supposed intel after the FBI had terminated its confidential human source relationship with Steele for lying.

The stains on Weissmann, though, date back much further: To 2002, when Weissmann joined the Enron Task Force. From 2002 until 2005, Weissmann made a name for himself in the Houston area, for his win-at-all-costs prosecutorial approach, which included veiled threats to witnesses, attempts to force disfavored (meaning, successful) defense attorneys off the case, and the use of “multiple grand juries working over several years” not to “return fresh indictments or start new cases, but to make the threat of indictment real and tangible” to the nearly 90 unindicted co-conspirators tied up in the Enron scandal.

Even more troubling was the failure of Weissmann’s Enron Task Force to turn over documents to the Merrill Lynch executives charged in a related case. Following their conviction, Sidney Powell—yes, that Sidney Powell—later discovered the missing documents and, on appeal, succeeded in overturning their convictions.

Weissmann’s work on the Enron case is damaging to the special counsel lead attorney in another way: It showcased Weissmann’s penchant for stretching the law until it breaks. And in the Enron case, what broke was not just the law, but former accounting standard bearer Arthur Anderson.

Arthur Anderson, which had served as Enron’s auditors, refused a plea deal, maintaining the firm’s innocence. Then at trial, Weissmann pushed a theory of criminal liability that resulted in the conviction and shuttering of the firm, leaving tens of thousands of employees without jobs. Then, two years later, in a unanimous opinion, the Supreme Court overturned the conviction, rejecting the legal theory Weissmann had advanced.

This strategy seems to mirror the one advanced in Part 2 of Mueller’s report, where the special counsel posited a novel theory of obstruction of justice to suggest Trump committed a crime. The attorney general has rejected the validity of this theory, but that doesn’t prevent the press and politicians on the left side of the aisle from continuing to advance it. But if Weissmann concocted the obstruction theory, his history with Arthur Anderson will prove an important counter.

The recent announcement that Weissmann has struck a book deal is also likely to color the hearing testimony and its aftermath. The money motive will be a further turn-off to the apolitical center that makes up the vast majority of this country.

Against all of these negatives, Weissmann has nothing. The special counsel report did its utmost to damage the president and failed. Anything Weissmann wanted to say was already in the report, insinuendo and all. So that means that when Weissmann testifies, he will only be able to repeat in private what he likely wrote for the public.

On the other hand, Republicans on the House committees can question Weissmann on the report and its omissions and misrepresentations, as well as Weissmann’s bias, past prosecutorial conduct, leaks, and involvement in the origins of the investigation into the Trump campaign. Although Weissmann’s testimony will be private, by summoning him to the hill, Democrats have guaranteed his involvement in the investigation and past conduct will be closely scrutinized. As more details become known, it will soon be clear that Mueller needed to keep his pit bull on a tighter leash.