Kurt Thomas is a former Twitter engineer and a current PhD student at UC Berkeley who studies how the criminal underground conspires to make money via unintended uses of computer systems. He is also a very talented lecturer as this video makes clear:
http://youtu.be/fU2gcB_toNw
I was fascinated by his account of how a couple of computer science researchers were able to break up a huge fraud ring essentially via big data analysis! See his lecture notes.
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