Two weeks ago Mueller indicted 13 Russian nationals on charges of conspiracy to defraud the United States.As extensive and startling as the indictment was, it said nothing about other known incidents involving Russians and the Trump campaign, including the strategic leaking of emails hacked from the Democratic National Committee and Hillary Clinton’s campaign manager and the various reported contacts between Russians and members of the Trump campaign.Now reports suggest Mueller may be focused on a different potential conspiracy, this one involving Russian actors and Trump campaign officials or the president himself. NBC News reported Thursday that Mueller’s investigators have been asking witnesses what Trump knew about the stolen emails.These “what did the president know and when did he know it” questions zero in on the key issues in proving any conspiracy: knowledge and intent. We may not have heard Mueller’s last word when it comes to conspiracies to interfere with the election.If the president or other members of his campaign knew about the hacking or other Russian interference and actively worked with the Russians to help those activities succeed, they could find themselves caught up in conspiracy charges of their own.On the obstruction of justice front, The Washington Post reported Wednesday that Mueller has been asking witnesses about the president’s apparent attempts to pressure Attorney General Jeff Sessions into resigning last summer.Those efforts came shortly after Trump had fired FBI director James Comey and reportedly had come close to firing Mueller himself. They could suggest sources of Russian leverage against the president or be relevant to any possible quid pro quo involving assistance with the election or other benefits provided to Trump in return for favorable actions toward Russia.And probing those connections could lead to evidence of other crimes such as money laundering, as Manafort has discovered.Mueller remains unlikely to indict the president, but any findings that Trump was involved in criminal activity could lead to calls for impeachment.And the constraints around indicting a sitting president do not apply to those closest to him, including members of his family who were deeply involved in his campaign.Last week brought the clearest signs yet that Mueller’s net is tightening around the White House – and maybe the president himself.Randall D. Eiason teaches white-collar criminal law at George Washington University Law School.More from The Daily Gazette:EDITORIAL: Find a way to get family members into nursing homesEDITORIAL: Beware of voter intimidationEDITORIAL: Urgent: Today is the last day to complete the censusEDITORIAL: Thruway tax unfair to working motoristsFoss: Should main downtown branch of the Schenectady County Public Library reopen? By forcing Sessions to step down, Trump could have sought to replace him with an attorney general who could rein in Mueller’s investigation and be more protective of the president.It seems clear that Mueller is probing whether there was a pattern of attempts by the president to obstruct justice by impeding the Russia investigation.Obstruction, of course, can occur even if the underlying activity being investigated turns out not to be illegal.Mueller could ultimately decide to bring no additional charges involving interference with the election and still conclude the president corruptly tried to derail the investigation in order to protect himself and his family.As Watergate taught us, sometimes it’s the coverup that gets you.Finally, CNN reported Wednesday that Mueller’s investigators have also been asking witnesses about Trump’s business ties to Russia before the 2016 campaign.Although Trump and others have suggested that such inquiries may be out of bounds, any financial entanglements between Trump and Russia are potentially important to Mueller’s probe. Categories: Editorial, OpinionSpecial counsel Robert Mueller III is significantly turning up the heat on President Trump.While the president once again attacks his own attorney general and declares himself the victim of a “witch hunt,” he faces increasingly ominous signs that Mueller has the president’s innermost circle — and Trump himself — in his sights.Mueller’s investigation has at least three tracks:Russian interference with the 2016 election and the possible involvement of any Trump officials.Obstruction of justice and related coverup crimes.Ancillary crimes discovered during the investigation, such as the money-laundering and other charges filed against Paul Manafort.In the past few days there have been reports of intensifying investigative activity focused on Trump’s own actions in all three areas.