Criminals attracted to ISIL's war crime philosophy

Washington Post:

ISIS relies on street toughs and ex-cons to spread terror in the West

European jails have long been breeding grounds of Islamist radicals, but criminality and extremism are becoming more interwoven, with recruits’ petty crime continuing even after they are shown “the light” of radical Islam.

ISIL is a state without inhibitions  and criminals who don't obey the law feel comfortable in that environment, at least until they become the target.  The fact is that ISIL has less restraint in the use of force than the Nazis.  They are more of an RICO entity than a state.