During the 2016 presidential campaign, Trump campaign chairman Paul Manafort pushed the idea that Ukraine, not Russia, was behind the hack of the Democratic National Committee servers, Manafort's deputy told investigators during the special counsel's Russia probe. The unsubstantiated theory, advanced by President Donald Trump even after he took office, would later help trigger the impeachment inquiry now consuming the White House.

Notes from an FBI interview were released Saturday after lawsuits by BuzzFeed News and CNN led to public access to hundreds of pages of documents from special counsel Robert Mueller's investigation. The documents included summaries of interviews with other figures from the Mueller probe, including Trump's former personal lawyer, Michael Cohen.

Information related to Ukraine took on renewed interest after calls for impeachment based on efforts by the president and his administration to pressure Ukraine to investigate Democrat Joe Biden. Trump, when speaking with Ukraine's new president in July, asked about the DNC servers in the same phone call in which he pushed for an investigation into Biden.

Manafort speculated about Ukraine's responsibility as the campaign sought to capitalize on DNC email disclosures and as Trump associates discussed how they could get hold of the material themselves, deputy campaign chairman Rick Gates told investigators, according to a summary of one of his interviews.

Gates said Manafort's assertion that Ukraine might have done it echoed the position of Konstantin Kilimnik, a Manafort business associate who had also speculated that the hack could have been carried out by Russian operatives in Ukraine. U.S. authorities have assessed that Kilimnik, who was also charged in Mueller's investigation, has ties to Russian intelligence. American intelligence agencies have determined that Russia was behind the hack, and Mueller's team indicted 12 Russian agents in connection with the intrusion.

Gates also said the campaign believed that Michael Flynn, who later became Trump's first national security adviser, would be in the best position to obtain Hillary Clinton's missing emails because of his Russia connections. Flynn said he could use his intelligence sources to obtain the emails and was "adamant that Russians did not carry out the hack" because he believed that the U.S. intelligence community couldn't have figured out the source, according to the agent's notes. Flynn later pleaded guilty to lying to the FBI about his contacts with the Russian ambassador.

Mueller's investigation concluded in March with a report that found insufficient evidence to establish a criminal conspiracy between Russia and the Trump campaign to sway the 2016 presidential election. The report also examined multiple episodes in which Trump sought to seize control of the Russia probe but did not conclude one way or the other about whether the president had illegally obstructed justice. Attorney General William Barr ultimately concluded that the president had not committed a crime.

Gates worked with Manafort in a lucrative international political consulting business that included Ukraine and later testified against him. Gates pleaded guilty last year in Mueller's investigation and has been one of the government's key cooperators. He has yet to be sentenced as he continues working with investigators. Manafort was sentenced to more than seven years in prison, in part for financial crimes arising from his Ukraine work.

During his interviews with investigators, Gates said that Donald Trump Jr. would ask where the hacked emails were during family meetings in the summer of 2016. Gates recalled that other key campaign aides, including future Attorney General Jeff Sessions, Trump son-in-law Jared Kushner and Flynn, also "expressed interest in obtaining the emails as well," according to an agent's written summary of one interview. The identity of one of the people who expressed interest in the emails is blanked out.

One time on the campaign aircraft, Gates told the FBI, candidate Trump said "get the emails." Gates also said that another point, Trump told him that more leaks were coming, though the heavily redacted documents do not indicate how Trump knew that.

Gates also described conversations with the chairman of the Republican National Committee, Reince Priebus, who later entered the White House as the first chief of staff. Gates described the RNC as energized by the emails and said that though Trump and Kushner were initially skeptical about cooperating with the RNC, "the WikiLeaks issue was a turning point," the FBI notes show. WikiLeaks was the website that published the stolen emails in the weeks before the election.

The campaign was also very pleased by the releases, though Trump was advised not to react to it but rather to let it all play out, according to the interview summaries.

The RNC would put out press releases to amplify the emails' release, Gates told the FBI. "The RNC also indicated they knew the timing of the upcoming releases," though Gates didn't specify who at the RNC had that information. "Gates said the only non-public information the RNC had was related to the timing of the releases."

Manafort, meanwhile, was trying to advise the Trump campaign even after severing ties with the campaign, causing alarm among some of the candidate's most senior advisers.

Manafort emailed Kushner, on Nov. 5, 2016, just days before the election, saying he was feeling good about the prospect of a Trump presidency. In the email, Manafort said he was "focusing on preserving the victory" and that he had sent a memo to Priebus and had briefed Gates and Fox News host Sean Hannity, a close Trump ally.

Kushner sent Manafort's email to Trump adviser Steve Bannon, who replied: "we need to avoid this guy like the plague."

"They are going to try and say the Russians worked with wiki leaks to give this victory to us," Bannon wrote to Kushner and David Bossie, another Trump associate, in his reply. "Paul is nice guy but can't let word get out he is advising us."