Robert Mueller's special counsel probe is now a year old: Here's what's happened and what the future may bring

Robert Mueller was appointed by the U.S. Justice Department as special counsel by deputy attorney general Rod Rosenstein exactly one year ago to investigate whether there was Russian interference in the 2016 U.S. election.

The anniversary did not escape the attention of President Donald Trump on Thursday, who has railed about "the cloud" of Russia hanging over his presidency.

The announcement of Mueller's hiring on May 17, 2017, came about after a dizzying series of events just weeks into Trump's first term. Attorney General Jeff Sessions recused himself from inquiries into Russia interference after not being forthright during his nomination hearings about his contacts with Russian officials. Trump then fired FBI Director James Comey; it is known that the FBI was investigating the likes of Trump's short-lived national security adviser Michael Flynn.

Mueller was given the authority to investigate "any links and/or co-ordination between the Russian government and individuals associated with the [Trump] campaign, and any matters that arose or may arise directly from the investigation.".

Here's a look at the key events since Mueller's appointment:

Oct. 30, 2017: Starting at the top

After months of silence and speculation, the boom is lowered for the first time and it involves former Trump campaign chairman Paul Manafort. Manafort and his deputy Rick Gates who face conspiracy and money laundering charges as a result of the probe.

It is also revealed that a former Trump campaign adviser, George Papadopoulos, pleaded guilty in early October to lying to the FBI and is co-operating.

Manafort is now facing charges in two jurisdictions. A judge in the Virginia matter questioned Mueller's latitude, though it's not clear if he has the legal basis to toss the charges despite his apparent misgivings.

For his part, Gates agreed to co-operate and plead guilty to charges including conspiracy and making false statements.

Dec. 1, 2017: In with Flynn

Few people were as vociferous in their championing of Trump at the Republican convention in 2016 than the Gen. Michael Flynn. So if the October news is significant, the knowledge that Flynn is co-operating with authorities seems quite momentous.

Flynn admits in court he lied when asked by FBI investigators about December 2016 conversations with Russia's then-ambassador, Sergey Kislyak. The two men discussed U.S. sanctions against Russia, among other topics.

Feb. 16: Russian troll job

The thrust of the investigation turns to Russia. Mueller charges 13 individuals and three Russian companies with conspiracy to meddle in the election, including the Internet Research Agency (IRA).

The allegations involving the IRA and others include a social media propaganda campaign that largely sought to discredit Trump opponent Hillary Clinton.

March 17-18: Long-awaited Trump tweet

The Mueller appointment was generally received positively. Former House Speaker Newt Gingrich leads the praise from conservatives, calling the former FBI director a "superb choice."

But pundits said to have the president's ear such as Sean Hannity have railed on air about the legitimacy of any investigation nearing the Trump orbit, trying to weave a narrative of malfeasance, overreach and bias from sometimes disparate storylines involving FBI agents texting and criticizing the president, the perceived wrongdoings of Comey and his second-in-command Andrew McCabe, and of course, the unfairness of the Mueller probe.

The president himself is relatively tight-lipped until March 17, when he specifically targets Mueller in a tweet for the first time.

"The Mueller probe should never have been started in that there was no collusion and there was no crime," Trump tweeted that night. The next morning he asked on the social media platform, without providing supporting evidence: "Why does the Mueller team have 13 hardened Democrats, some big Crooked Hillary supporters, and Zero Republicans?"

The tweets raise fears anew that Trump will find a way to shut down the investigation.

April 3: Alex who?

Liberals eagerly awaiting the prospect of a Trump crony being carted off to prison were likely nonplussed by the revelation that the first to be sentenced was one Alex van der Zwaan.

The Russian-speaking Dutch attorney, whose father-in-law is a Moscow billionaire, is sentenced to 30 days in prison and fined $20,000 US for lying about his dealings with Gates.

April 9: Trump worlds collide?

Trump in his first 16 months on the job has been dogged not only by the Russia investigation, but by allegations of sexual misconduct and extramarital affairs. FBI agents on April 9 raid the offices and home of Trump's personal attorney, Michael Cohen. Cohen has admitted paying $130,000 to porn star Stormy Daniels to keep her quiet about an affair she said she had with Trump.

Cohen's lawyer says New York authorities were acting on a referral from the office of the special counsel.

While the Daniels saga may be salacious, in the weeks to come, the Cohen storyline balloons to include allegations of payments from corporations, Russian oligarchs and Qatari officials. The payments cause fallout for companies such as AT&T and Novartis.

Current state

So far, 19 men have been charged in the probe, including an obscure Californian (Ricardo Pinedo) found to have sold bank account numbers of stolen U.S. identities to foreigners.

That curio aside, what many want to know is: has the president obstructed justice at any point?

There has been no indication of the counsel's interpretation, let alone charges, regarding headline-grabbing events of the past two years such as a June 2016 meeting at Trump Tower involving Russians and the president's potential involvement in drafting a misleading statement about that meeting, the president's firing of Comey or the cyberattack targeting the Democratic National Committee.

No one related to the president by blood or marriage has been implicated in the probe.

As the Mueller team works, congressional committees have also been pursuing the subject of potential collusion, but with varying degrees of enthusiasm. While senators seem to be operating in a spirit of bipartisanship, House probes have devolved into separate tracks of competing documents and attempts to drive the media narrative.

Throughout the year Trump has spoken generally about being willing to be interviewed by Mueller's team, but with no firm commitment. Media reports have suggested the Trump side has tried to dictate the scope of the questioning.

A bill introduced in the Senate to protect Mueller from being removed from the job before it is completed has fizzled, as Senate Majority Leader Mitch McConnell has shown no interest in pursuing them.

"There's no indication that Mueller's going to be fired," McConnell said in mid-April.

Two separate Justice Department opinions over the years have suggested that a sitting president is immune from indictment and that criminal charges would undermine the ability of the commander-in-chief to do the job. But there's nothing in the U.S. Constitution forbidding it and it's never been tested in the courts.

Trump legal adviser Rudy Giuliani said this week the special counsel doesn't have the authority to subpoena Trump and that he's received assurances from Mueller he is not seeking a Trump indictment. Whether that's fact or just a high-pressure media blitz is unclear.

The future

Mueller hasn't said anything publicly beyond a one-line statement upon his appointment last year.

Should he be able to conclude his investigation, Mueller would submit a report to the deputy attorney general. The report's findings could determine if impeachment is pursued, a political calculation that will depend on the results of November midterm elections to be fiercely contested by Republicans and Democrats.

Giuliani and the White House communications department say it's time for Mueller to wrap up the probe as there's nothing more to be gleaned and it's clear that Trump is blameless of the charge of collusion.

It's not clear they will get their way anytime soon. They have been saying it's time to wrap up the probe for at least five months now.