Article is interesting but says nothing about AWB just that people committing crimes own/obtained guns illegally.
http://www.wggb.com/2012/05/02/assault-rifles-legal-vs-illegal/
Delaney says the guns recovered from the hotel were stolen during recent house breaks, which is how most legal guns fall into the wrong hands.
http://www.wggb.com/2012/05/02/assault-rifles-legal-vs-illegal/