I think there is a very fine line between a criminal and a cop per say in mentality. Good cops will know what to look for in criminal behavior and good criminal

I think there is a very fine line between a criminal and a cop per say in mentality. Good cops will know what to look for in criminal behavior and good criminals will know how to look out for cops; not all cops - but I would say its a fine line between the best of both worlds. Could be the reason double agents are so valuable.