While I don't agree with the use of informants and would like to see everyone treated equally by the justice system, I would not deny that they do exist. However, even some of the informants and cover up agents in the article posted by Katerina ended up in jail, which indicates that even they are not totally beyond the law and do not have a "license to kill".
Let's for argument sake go along with Mike being an informant. I can see that he could have a financial interest in this situation, but what do the authorities have to gain? What information could Mike possibly provide to them that would have enough value to them worth turning a blind eye to his alleged crimes?
This is not intended to take a stance either way but to obtain some clarity.