The special counsel Robert Mueller released a memorandum on Friday detailing the cooperating and witness testimony provided by Michael Cohen, President Donald Trump's former personal lawyer.

The memo says Cohen testified with respect to four crucial areas of Mueller's investigation into Russia's interference in the 2016 election and whether the Trump campaign colluded with Moscow.

Cohen told Mueller about the talks to build a Trump Tower in Moscow; other contacts with Russia; his communications with the White House after Trump took office; and how and why he lied to Congress about the Trump Tower deal.

The special counsel Robert Mueller released a memorandum on Friday detailing the cooperating and witness testimony provided by Michael Cohen, President Donald Trump's former personal lawyer and longtime fixer.

Mueller's sentencing memo and a separate memo filed last week by Cohen's lawyers say Cohen has provided 70 hours of testimony to the special counsel, who is investigating Russian interference in the 2016 election and whether the Trump campaign collaborated with Moscow to tilt the race in Trump's favor.

Read more: Federal prosecutors recommend 'substantial' prison sentence for former Trump lawyer Michael Cohen, saying he demonstrated a 'years-long pattern of deception'

On November 30, Cohen struck a deal to plead guilty to one count of lying to Congress in exchange for cooperating with the special counsel. Cohen admitted to falsely stating in his September 2017 congressional testimony that the Trump Organization ended talks to build a Trump Tower in Moscow sometime in January 2016.

In reality, prosecutors say, those discussions continued well into June 2016, and that Cohen "admitted he told these lies—which he made publicly and in submissions to Congress—in order to minimize links between the Moscow Project and Individual 1," referring to Trump.

Cohen provided testimony to Mueller on the following subjects:

The Trump Organization's attempt to build a Trump Tower in Moscow

The memo says Cohen provided "a detailed account of his involvement and the involvement of others in the Moscow Project," an effort that continued until June 2016, after Trump became the presumptive Republican presidential nominee.

The memo goes on to describe "in or around November 2015, Cohen received the contact information for, and spoke with, a Russian national who claimed to be a “trusted person” in the Russian Federation who could offer the campaign “political synergy” and “synergy on a government level.”

While this person is not named in the memo, BuzzFeed News reported in June that Cohen reached out to Russian weightlifter Dmitry Klokov about the project. Klokov claimed to be connected to Russian President Vladimir Putin. They were reportedly introduced by Ivanka Trump, then a vice president at the Trump Organization.

The memo says that Klokov told Cohen that a meeting between Trump and Putin would have a "phenomenal" impact "not only in political but in a business dimension as well," referring to the Moscow Project, because there is "no bigger warranty in any project than consent of [the President of Russia]."

Cohen did not follow through with Klokov's offer, telling him there was an existing agreement to build a Trump Tower between Russia and the Trump Organization.

Read more: Trump and his allies' explanations for the campaign's Russia contacts have seen a stark evolution as new evidence has spilled out

Mueller's sentencing memo said Cohen's false testimony to Congress "obscured" the fact that the Trump Tower Moscow deal represented a potentially lucrative business opportunity that may have required approval from the Russian government.

"If the project was completed, the Company could have received hundreds of millions of dollars from Russian sources in licensing fees and other revenues," the memo said. It also added that Cohen's continued work on the proposal, as well as his communications with Trump about it, were doubly relevant because they happened while the Russian government was actively interfering in the 2016 election to sway the race in Trump's favor.

Other "discrete Russia-related matters"

The memo says that "Cohen provided the [special counsel] with useful information concerning certain discrete Russia-related matters core to its investigation that he obtained by virtue of his regular contact with Company executives during the campaign."

This line stands out, given that many executives of "the Company" are in Trump's immediate family and have been implicated in other parts of the probe.

Donald Trump Jr., also a vice-president at the Trump Organization, attended a June 2016 Trump Tower meeting with top campaign officials and two Russian lobbyists who were offering dirt on the Hillary Clinton campaign. The parties involved have said nothing came of the meeting and that the Trump campaign did not get the kompromat it was promised, but the campaign's willingness to meet with Kremlin-aligned operatives has piqued investigators' interest.

Trump Jr. also testified to Congress last year that his father did not have any advance knowledge of the meeting. If investigators learn that Trump did know about it, however, the revelation could land his eldest son in the same legal trouble Cohen found himself in for misleading Congress.

Cohen, as well as at least two other Trump associates, have indicated that Trump may have known more about the meeting than he let on.

Read more: Michael Cohen's plea deal poses a significant danger to Donald Trump Jr.

Contacts with persons "connected to the White House"

Mueller's memo also said Cohen provided "relevant and useful information concerning his contacts with persons connected to the White House during the 2017-2018 time period."

This line is also significant, because "relevant and useful" information to the special counsel investigation could indicate that Cohen and people in or near the White House continued to pursue criminal activity after the campaign, and well into the first two years of the Trump administration.

"That sounds to me like someone else in the Trump orbit will be indicted as a co-conspirator either for lying to Congress or for obstruction of justice," said Jens David Ohlin, a vice dean at Cornell Law School and criminal-law expert.

"Preparing and circulating" his false congressional testimony

Finally, the memo states that Cohen "described the circumstances of preparing and circulating his response to the congressional inquiries, while continuing to accept responsibility for the false statements contained within it."

Ohlin said it was also telling that the memo said that Cohen divulged who he collaborated with in the administration "while continuing to accept responsibility for his false statements."

"Sounds to me that they consider this a collective crime with multiple perpetrators," Ohlin said. "Additional indictments are likely, especially involving contacts between the Trump campaign and Russia, which is the last piece of the puzzle."

Mueller's memo came shortly after the Southern District of New York filed a separate sentencing memo regarding Cohen's cooperation in its investigation into his and Trump's financial dealings before the election.

Cohen pleaded guilty in August to tax evasion, bank fraud, and campaign finance violations. He said he violated election law by participating in payments to two women who claim to have had affairs with Trump shortly before the 2016 race. Cohen told investigators he did so at Trump's direction.

Friday's memo from the Manhattan US attorney's office echoed Cohen's claim, saying he committed his crimes "in coordination with and at the direction of" Trump, who is identified in the document as Individual-1.

"The biggest takeaway from this is that prosecutors actually named President Trump as an unindicted co-conspirator," said Jeffrey Cramer, a longtime former federal prosecutor in Chicago who spent 12 years at the DOJ. "And it's not just based on Cohen's word. These documents make it clear that investigators also have other independent, corroborating evidence."

"You really can't overstate this," he added. "The President of the United States was an unindicted co-conspirator in a felony? When's the last time that statement's been uttered?"