On February 16th, the Justice Department unveiled the first of four pillars of Special Counsel Robert Mueller's inquiry into interference in the 2016 election: the indictment of 13 Russians for Internet-based meddling. Since then the Mueller investigation has been quiet but there's new evidence that they are moving forward with the other three pillars of their inquiry: collusion, obstruction and hacking.
On April 30, the New York Times (https://www.nytimes.com/2018/04/30/us/politics/questions-mueller-wants-to-ask-trump-russia.html ) published the roughly fifty questions that the Mueller probe wants to ask Donald Trump, under oath. These questions are primarily about campaign coordination with Russia -- collusion -- and about possible obstruction of justice.
The collusion aspect of the Mueller probe explore the possibility of illicit cooperation between Russian operatives, involved in election interference and hacking, and the Trump campaign.
A key Mueller question for Trump focuses on the notorious June 9, 2016, Trump Tower meeting where a Russian operative offered to give key members of the Trump campaign political dirt on Hillary Clinton. Mueller also wants to know about communication between (Trump associate) Roger Stone and Wikileaks -- conversations about hacked DNC and Clinton Campaign emails. More generally, Mueller wants to find out what Trump knew "about Russian hacking, use of social media, or other acts aimed at the [Clinton] campaign."
Mueller's most provocative question is "What knowledge did you have of any outreach by your campaign, including by Paul Manafort, to Russia about potential assistance to the campaign?" (Paul Manafort is the former manager of the Trump presidential campaign; he has since been indicted by the Mueller probe for his Ukraine consulting work and other undisclosed actions.) Manafort was present at the June 9, 2016, Trump Tower meeting; the question suggests that the investigators know of other attempts to secure Russian assistance.
In the context of the 2016 election, collusion can mean "a long-term criminal conspiracy." One would hope that the coming Mueller indictments would address the concern that Donald Trump has subterranean ties to Putin, and Russian oligarchs, and this relationship subverted the US electoral process. Several Mueller questions relate to this. Notably: "What communication did you have with Michael D. Cohen, Felix Sater and others, including foreign nationals, about Russian real estate developments during the campaign?" (There are rumors that the Mueller team has excavated the financial links between Trump and Russian oligarchs.)
Although Trump continues to deny collusion, there seems to be ample evidence that there were, to say the least, unusual interactions between the Trump campaign and Russian operatives. (The latest revelation is that a Russian oligarch, Viktor Vekselberg, gave $500,000 to Trump associate Michael D. Cohen.) The key question is: can any of these interactions be tied to Trump?
Another pillar of the Mueller investigation focuses on obstruction of justice: has the Trump Administration blocked DOJ efforts to understand interference in the 2016 election? There are three sets of Mueller questions relating to obstruction.
The first set concerns Michael Flynn who was a key adviser to Trump during the campaign and, briefly, his national security adviser. (Flynn has agreed to cooperate with the Mueller probe and has pled guilty to lying to an FBI agent.) Mueller is interested in whether Trump was aware that Flynn had reached out to Russian officials before the inauguration. Another question asks if Trump has contacted Flynn about a possible pardon.
The second set of obstruction-related questions concerns Attorney General Jeff Sessions. These questions concern Sessions decision to recuse himself from the Mueller inquiry and Trump's (alleged) pressure on Sessions to end the Russia investigation.
The third set of questions relate to former FBI director James Comey. Mueller wants to ask Trump about the circumstances that led to Comey's dismissal. Specifically, Mueller would ask Trump: "What did you mean when you told Russian diplomats on May 10, 2017, that firing Mr. Comey had taken the pressure off?"
There's abundant evidence that Trump is displeased with the Mueller investigation. (Almost daily, he Tweets to this effect.) What remains to be seen is whether there is concrete evidence that Trump has obstructed the investigation; for example, by promising to pardon those who have been targeted by the Mueller probe.
Finally, the third pillar of the Mueller investigation regards hacking. This inquiry would explain who hacked the emails of the Democratic National Committee (DNC) and John Podesta, Hillary Clinton's campaign chairman. As noted above, Mueller wants to find out what Trump knew "about Russian hacking, use of social media, or other acts aimed at the [Clinton] campaign."
Summary: May 17th marks the anniversary of the day that the Mueller probe began. It's accomplished a lot in a remarkably rumor-free inquiry.
There seems to be abundant evidence that Russian operatives interfered in the 2016 presidential election and that there was contact between the Trump campaign and Russians. Of course, as the presidential candidate, Trump bears some responsibility for this. What remains to be seen is whether there's direct evidence that Trump committed an unlawful act. Trump acts like he's guilty but, so far, there's no smoking gun.