ORLANDO: Orlando nightclub shooter Omar Mateen was not the first employee of British security giant G4S to go on a rampage. Sunday morning's attack in Florida has raised questions over the quality of vetting procedures among the firm's recruits.
The Orlando killer was believed to be 29-year-old Omar Mateen, an Afghan-American G4S security guard. The killing spree, carried out with apparently legally acquired automatic rifles, claimed the lives of 49 partygoers and injured 53 according to the latest figures.
The gunman was shot dead after police stormed the club in a bid to rescue 30 hostages being held there.
The British firm is one of the world's biggest military and security providers. It employs more than half a million people -- many of them ex-military -- in 110 countries including conflict zones like Iraq and Afghanistan. It has been rocked by repeated controversy.
The firm's shares plunged to a seven year low in the wake of its admission that Mateen was an employee, losing over $285 million (£200) million.
Orlando may be the worst atrocity attributed to a G4S employee, but it was not the first.
In 2009 former paratrooper Danny Fitzsimons -- an employee of Armour Group, a division of G4S -- was convicted of killing two colleagues and sentenced to life in prison.
According to human rights NGO Reprieve, Fitzsimons was employed by the mercenary firm despite having been diagnosed with post traumatic stress disorder (PTSD) in May 2008 -- the same month G4S took over Armour Group.
He was thought to have developed the condition after exposure to a number of brutal events as a combatant in Kosovo, Afghanistan and Iraq.
Some 36 hours after arriving in Baghdad as a mercenary in 2009, Fitzsimmons killed fellow security operators Paul McGuigan and Darren Hoare following what was reported to have been a drunken brawl.
It emerged in 2012 following a BBC investigation that emails had been sent to Armour Group by G4S warning them not to employ Fitzsimons.
RT asked G4S about current vetting process used by the firm in reference to both the Mateen and Fitzsimons cases.
A spokesman said given the radically different operating environments in Iraq and the mainland US it is important not to conflate the two cases.
However, he said all staff undergo thorough tests including criminal records, right to work, identity and the Minnesota multiphasic personality inventory test -- a well-regarded psychometric assessment process.
The spokesman also restated the G4S position that Mateen was "re-screened" in 2013, the first year in which he was reportedly questioned by the FBI.
The Islamic State has claimed responsibility for the Orlando attacks, though Mateen's connection with the terror group was not yet clear.