Attorneys behind the Russia investigation let the American people down as former Special Counsel Robert Mueller failed to level a more aggressive indictment of President Trump's conduct, former Justice Department official Andrew Weissmann argued.

Weissmann, who has been described as Mueller's "legal pit bull," portrays the former special counsel in a new book as scrupulous but allowing his team to be steered in the wrong direction, The Atlantic reported on Monday.

The Atlantic's George Packer specifically asked Weissmann whether the Russia team let the American people down, to which Weissman said, "yep, absolutely." He added: “I wouldn’t phrase it as just Mueller. I would say ‘the office.’ There are a lot of things we did well, and a lot of things we could have done better, to be diplomatic about it.”

For Weissman, it was "fair" to describe the investigation as a historic missed opportunity.

DOJ RECORDS SHOW MEMBERS OF MUELLER'S TEAM 'WIPED' PHONES DURING TRUMP PROBE

Mueller's portion of the years-long investigation notably ended in the middle of last year when he announced his team's findings. The report claimed insufficient evidence for Trump to meet the legal definition of conspiring with Russia, although it noted several instances that critics have held up as troubling. He also outlined multiple instances surrounding potential obstruction of justice but stopped short of pushing prosecution, noting a DOJ rule on the issue.

Some speculated that the report was a way of preparing Congress for impeachment, although Weissmann would have liked to see more in the report itself.

“I also think it seems like a transparent shell game,” Weissman reportedly told one of his colleagues. “When there is insufficient proof of a crime, in volume one, we say it. But when there is sufficient proof, with obstruction, we don’t say it. Who is going to be fooled by that? It’s so obvious.”

The investigation ultimately ended after months of inquiry by House Democrats, who have maintained they could continue pressing the issue in the future.

MUELLER DEPUTY ANDREW WEISSMANN TO HEADLINE BIDEN VIRTUAL FUNDRAISER

Weissmann alleges that Mueller's actions bolstered Trump's ability to defend himself to the country.

Packer writes: "Mueller, judging that Trump wouldn’t have his day in court until he became a private citizen again, refrained from stating that Trump had broken the law (even though volume one of the report explicitly cleared the president of the conspiracy charge)."

"Weissmann politely demolishes this effort at extreme fairness. 'I was flummoxed by Mueller’s thinking,' he added. The special counsel was required to make a legal recommendation on the facts and present it in an internal department document to the attorney general. Barr could decide to keep the report private. Or, if it became public, Trump could use his unparalleled platform to defend himself to the country. Or he could choose to be charged and tried in order to clear his name. Mueller, completely out of character, was 'making his own, freelance judgments about what was appropriate and not delivering on what he was tasked with doing.'"

CLICK HERE TO GET THE FOX NEWS APP

Weissmann also takes aim at Aaron Zebley, another prosecutor on Mueller's team.

“Repeatedly during our twenty-two months in operation,” Weissmann reportedly wrote, “We would reach some critical juncture in our investigation only to have Aaron say that we could not take a particular action because it risked aggravating the president beyond some undefined breaking point.”