Cops shooting each other during drug busts.

Heh, just the mental image warms my cold heart. 

But, you notice they never shoot each other when investigating murders or car thefts? Just during drug busts, gambling busts.
I wonder what if there's a causal mechanism behind this correlation.

http://thefreethoughtproject.com/undercover-albuquerque-police-officer-shot-fellow-cop/