It was one year ago Thursday when Robert Mueller, the former FBI director, was appointed as special counsel to take over the Justice Department's investigation into possible coordination between Russia and Donald Trump's 2016 presidential campaign.
The 12 months since have yielded a flurry of criminal indictments and guilty pleas, tense court appearances, angry tweets from the president and speculation over what the ever-taciturn Mueller already knows and what he'll investigate next.
Hundreds of pages of court filings, and public statements from witnesses, have to an extent pulled back the curtain on an extraordinarily secretive investigation. But much remains hidden from view.
A look at the last year and what may lie ahead: