Robert Mueller breaks silence to insist he did not exonerate Trump

* Mueller’s statement seen by many as signal to Congress to act* Special counsel ‘not confident’ Trump did not commit a crimeRobert Mueller, the special counsel, on Wednesday reignited demands for Donald Trump’s impeachment by breaking his two-year silence to deny that the US president is innocent of a crime.In a sudden and dramatic turn, Mueller, whose report on Russian election interference and Trump campaign links to Moscow was published last month, delivered a sombre