The team led by special counsel Robert Mueller failed to do everything it could to determine what happened in the 2016 election, shying away from steps like subpoenaing US President Donald Trump and scrutinising his finances out of fear he would fire them, one of Mueller's top lieutenants argued in the first insider account of the inquiry.
"Had we used all available tools to uncover the truth, undeterred by the onslaught of the president's unique powers to undermine our efforts?" wrote the previous prosecutor, Andrew Weissmann, in a new book, adding, "I know the hard answer to that simple question: We could have done more."
The team took elaborate steps to protect its files of evidence from the risk that the Justice Department might destroy them if Trump fired them and worked to keep newsmen and the public from learning what they were up to, Weissmann wrote in "Where Law Ends: Inside the Mueller Investigation," which Random House will publish next week.
While he speaks reverently of Mueller, he also says his boss's diffidence made him ill-suited for aspects of shepherding the politically charged investigation. He saw Mueller and his deputy, Aaron M. Zebley, as overly cautious.
Weissmann also defended against accusations by the president and his allies that he and other investigators were politically biased "angry Democrats"; Weissmann said his personal views had no bearing on the crimes that Russian operatives and Trump aides committed.
And he elevates particular detailsfor example, emphasising that the same business account that sent hush payments to an adult film star who alleged an extramarital affair with Trump had also received "payments linked to a Russian oligarch".
The president has denied the affair; his previous lawyer Michael Cohen controlled the account. Mueller transferred the Cohen matter to prosecutors in New York.
Weissmann ran one of three major units for the special counsel's office. His "Team M" prosecuted Trump's previous campaign chairman Paul Manafort for numerous financial crimes. The goal was to flip him and learn whatever he knew about any Trump campaign links to Russia.
Manafort had worked for pro-Russian interests in Ukraine, and the investigation uncovered ties by his business partner, Konstantin Kilimnik, to Russian intelligence.
The book builds towards investigators' discovery that Manafort had shared internal campaign polling data with Kilimnik, who flew to the United States to meet with Manafort during the campaign, asking whether Trump would permit a peace plan for Russia to essentially take over all of eastern Ukraine.