Even Constitutional law professor Jonathan Turley who leans left has an interesting things view on if a crime has been committed:
Just this week, constitutional law professor Alan Dershowitz (who says he proudly voted for Hillary) said now the left "couldn't criminalize political differences" in regard to President Trump. . .
Agree, there are plenty of plausible legal arguments as to why Trump cannot be prosecuted. And I still haven’t seen any direct evidence of Trump himself being part of a criminal conspiracy (obstruction/Comey firing may be another matter, however). None of this precludes him from having to be interviewed as part of the broader investigation and current prosecutions. Hell, if President Clinton had to give a deposition in a civil matter over sexual misconduct, then I don’t see any realistic precedent for Trump avoiding this one.