Security firm G4S was sent warnings not to employ an armed guard in Iraq just days before he murdered two colleagues, a BBC investigation has found...it is revealed that a G4S worker sent a series of emails to the company in London, warning them about Fitzsimons's previous convictions and unstable behaviour...Within 36 hours of arriving in Iraq in August 2009, Fitzsimons...had shot and killed the two men after what he claimed was a drunken brawl...In the documentary, the parents of [victim] Paul McGuigan call for the company to face criminal charges over the killing...A G4S spokesman admitted that its screening of Danny Fitzsimons "was not completed in line with the company's procedures". It said vetting had been tightened since the incident. Regarding the email warnings, the spokesman...[said] it was aware of the allegations but that an internal investigation showed "no such emails were received...".