„The systematic murder of Shias by Isis has mirrored that of al-Qaeda in Iraq since the first days of the US occupation in 2003. The preferred method before Isis became a powerful military force was to send suicide bombers to mosques, markets or pilgrimage sites where the explosion would cause maximum casualties.“
http://www.independent.co.uk/news/world/middle-east/isis-mass-graves-iraqi-forensic-teams-recover-remains-of-1700-military-cadets-slaughtered-by-militants-near-tikrit-10160883.html