Staffers working on Robert Mueller's investigation into whether Trump colluded with Russia were required to hand over their phones to the DoJ
Documents released this week reveal at least 15 of the phones had been wiped before being assessed for any possible evidence of anti-Trump bias
Information stored on the devices disappeared because staffers 'forgot'pass codes, damaged screens or 'lost' the devices
President Trump raged about the news in a Twitter post on Saturday, calling the excuses 'really dumb'
He then claimed left-wing operatives have a history of cover -ups, referencing emails allegedly wiped from Hillary Clinton's email server prior to 2016