That's assuming he was an unwilling participant and not an enemy agent working within the Joliet PD from the start. With Narcos, like most criminals, they tend to come from clans of criminals. I wouldn't be surprised that if this story isn't memory holed, it's learned that Mr. Esqueda has kin who're narcos.

Either way, something like this is all a criminally inclined mayor would need to place temporary, turned permanent, restrictions on the local police.