Attorney General William Barr is set to release the Mueller report on Thursday, shedding light on many aspects of the investigation that has sparked massive speculation during Donald Trump’s first two years as president.

Roughly a month after receiving the report in the first place, Mr Barr’s release comes as Democrats have repeatedly and loudly demanded a full an un-redacted copy of the document, a request that appears unlikely to be totally met by the Justice Department.

On Wednesday night – the eve of the report’s release – the Washington Post said the department of justice would release a report that was only “lightly redacted”.

It said it will reveal that Mr Mueller decided he could not come to a conclusion on the question of obstruction of justice because it was difficult to determine Mr Trump’s intentions and some of his actions could be interpreted innocently. But it said it would offer a “detailed blow-by-blow of his alleged conduct”.

While most of the report remains under wraps, here’s what we know so far about what is inside — and what we might expect to learn.

The report says that Mr Trump’s campaign did not collude with Russia during the campaign

Mr Barr indicated in a letter to Congress that the Mueller report found that there was no collusion between the Trump campaign and Russia during the 2016 election, in spite of numerous reports over the past two years indicating that Trump campaign officials met with Russian sources during that time.

With those reports as backdrop, the idea that Mr Mueller’s team determined no collusion or conspiracy existed has been a contentious one since Mr Barr’s letter was released.

Mueller investigation: The key figures Show all 12 1 /12 Mueller investigation: The key figures Mueller investigation: The key figures Robert Mueller is the special counsel overseeing the investigation into Russia's meddling in the 2016 election, and potential obstruction of justice by the president. Mr Mueller has a pristine reputation in Washington, where he was previously in charge of the FBI. Throughout his investigation, he and his team have been notoriously tight lipped about what they know and where their investigation has led. REUTERS Mueller investigation: The key figures Former FBI director James Comey was the catalyst that led to the appointment of special counsel Robert Mueller. Mr Comey was fired by the president after Mr Trump reportedly asked him to drop his own Russia investigation. Mr Trump has long maintained that the investigation is a "witch hunt". AFP/Getty Images Mueller investigation: The key figures Deputy attorney general Rod Rosenstein had authority over the special counsel investigation for much of the two years it has been active. Mr Rosenstein found himself with that responsibility after then-attorney general Jeff Sessions recused himself from that oversight. AP Mueller investigation: The key figures Attorney general Jeff Sessions's decision to recuse himself from oversight of the special counsel investigation may have cost him his job in the end. Mr Sessions resigned last year, after weathering a contentious relationship with Donald Trump who vocally criticised his attorney general for taking a step back. Mr Sessions recused himself from the oversight citing longstanding Justice Department rules to not be involved in investigations overseeing campaigns that officials were apart of. AP Mueller investigation: The key figures Attorney General William Barr is currently responsible for oversight of the special counsel investigation. Mr Barr's office will be the first to receive the Mueller report when it is finished. His office will then determine what portion or version of that report should be delivered to Congress, and also made public. EPA Mueller investigation: The key figures Michal Cohn is the president's former personal lawyer, who has been helping the special counsel investigation as a part of a plea deal over financial crimes, and campaign finance crimes, he has pleaded guilty to. Among those crimes, Cohen admitted to facilitating $130,000 in hush money payments to adult film actress Stormy Daniels during the 2016 campaign. Cohen has said he did so at the direction of Mr Trump. Cohen has also admitted that he maintained contacts with Russian officials about a potential Trump real estate project in Moscow for months longer than Mr Trump and others admitted. The talks continued well into 2016 during the campaign, he has said. AP Mueller investigation: The key figures Stormy Daniels has alleged that she had an affair with Donald Trump in 2006, soon after Melania Trump gave birth to Baron Trump. The accusation is of particular importance as a result of the $130,000 hush money payment she received to keep quiet about the affair during the 2016 campaign. AP Mueller investigation: The key figures Paul Manafort was Donald Trump's former campaign chairman. Manafort was charged alongside Rick Gates for a slew of financial crimes, and was convicted on several counts in a Virginia court. He then pleaded guilty to separate charges filed in a Washington court. Manafort has been sentenced to just 7.5 years in prison for his crimes — in spite of recommendations from the special counsel's office for a much harsher sentence. AP Mueller investigation: The key figures George Papadopoulos was one of the first individuals associated with the Trump campaign to be charged by the Mueller probe. He ultimately received a 14 day prison sentence for lying to investigators about contacts he had with Russian officials. AP Mueller investigation: The key figures Roger Stone is a well known political fixer and operative, who has made a name for himself for some dirty tactics. He has been charged by the Mueller probe earlier this year, and he has been said to have had prior knowledge that WikiLeaks planned on publishing stolen emails from the Hillary Clinton campaign in 2016. Getty Images Mueller investigation: The key figures Rick Gates was charged alongside former Trump campaign chairman Paul Manafort for a range of crimes. Gates, who worked alongside Manafort for a pro-Russia Ukrainian political party. The two were charged with conspiracy and financial crimes. Gates pleaded guilty. AP Mueller investigation: The key figures Former national security adviser Michael Flynn was one of the first casualties of the Russia scandal, and was forced out of his position in the White House weeks after Donald Trump took office. Flynn pleaded guilty in 2017 to "willfully" making fraudulent statements about contacts he had with Russian officials including former Russian ambassador to the US Sergey Kislyak. Flynn then lied to Vice President Mike Pence about that contact. REUTERS

The report will talk about Mr Trump’s decision to fire former FBI director James Comey

The existence of the Mueller investigation at all can actually be traced back to Mr Comey’s firing, which the former FBI director reportedly found out about by taking a look at news reports on television.

Mr Trump said following the firing that the Russia investigation played a part in his reasoning for the firing — leading to claims that the president obstructed justice in the firing.

Mr Barr has indicated he does not believe sitting presidents can obstruct justice while doing their job, and has indicated the Justice Department does not view the evidence on this issue as being weighty enough to bring charges against Mr Trump.

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We may get more information about interactions between Mr Trump and Mr Comey before that firing

Mr Comey, after his firing, released memos he wrote just after meetings with Donald Trump, alleging that the president pressured him to drop the Russia investigation.

The report is likely to tell us a bit more about those meetings, and who was involved.

We will likely learn how much contact the Trump campaign had with Russia — including a now-infamous meeting in Trump Tower

We already know that Donald Trump Jr and several other top Trump campaign officials met with Russian lawyer Natalia Veselnitskaya after being promised dirt on Hillary Clinton.

Mr Trump Jr and others have claimed they got no real intelligence from that effort, but it remains to be seen what the Mueller probe found.

How much did Roger Stone interact with WikiLeaks?

At the centre of all the hacking and leaking that Russia managed to get away with is WikiLeaks, the platform where stolen emails from the DNC and Clinton campaign were published.