In his forthcoming book, Where Law Ends: Inside the Mueller Investigation, Andrew Weissmann describes what it was like serving as a prosecutor on former Special Counsel Robert Mueller's team investigating Russian meddling in the 2016 election, going into detail about his frustrations and fears.

In the book, Weissmann — who now teaches at New York University School of Law and serves as an MSNBC legal analyst — writes that the special counsel's efforts were stymied by the constant threat of Trump's wrath, The Washington Post reports. They were reluctant to get too aggressive, he said, due to "the president's power to fire us and pardon wrongdoers who might otherwise cooperate."

Weissmann writes that this is why Mueller's top deputy, Aaron Zebley, stopped investigators from taking a broader look at Trump's finances, the Post reports. The pressure, he said, "affected our investigative decisions, leading us at certain times to act less forcefully and more defensively than we might have. It led us to delay or ultimately forgo entire lines of inquiry, particularly regarding the president's financial ties to Russia."

With Trump, Russia's main intelligence agency has "gotten what it had worked so hard for — a servile, but popular, American leader," Weissmann writes. "There is no other way to put it. Our country is now faced with the problem of a lawless White House, which addresses itself to every new dilemma or check on its power with a belief that following the rules is optional and that breaking them comes at minimal, if not zero, cost."

Weissmann told the Post he decided to write Where Law Ends after Attorney General William Barr released his own four-page summary of Mueller's report, which downplayed the findings; Mueller would later pen a letter saying Barr "did not fully capture the context, nature, and substance" of his work.

"I wrote it very much so there would be a public record from somebody, at least one viewpoint, from the inside as opposed to the story being told in maybe a less accurate way by people from the outside," Weissmann said. In the book, he accuses Barr of enabling a "lawless" president, and says the attorney general "had betrayed both friend and country." Read more about Weissmann's book, including why he thinks there was enough evidence showing Trump obstructed justice and how special counsel rules should be changed, at The Washington Post. Catherine Garcia