emmanuel sithole was attacked by a mob who repeatedly stabbed him and beat him using a metal wrench .
south african gang carried out the sickening murder because mr sithole was born in neighbouring mozambique .
killing took place in alexandra township near johannesburg after a night of xenophobic looting and attacks .
locals blame migrants from elsewhere in africa for a lack of jobs - with neighbours turning on one another .
in a chilling twist mr sithole did not receive treatment at nearby medical centre because foreign-born duty doctor failed to turn up for work as he feared being attacked .
warning graphic content .