In general, being in a position to at least monitor (and maybe even guide) the investigation into your crimes will always be advantageous.

This goes even further, in a somewhat bizarre direction. Suffice it to say "fraternal order of police" may be a more accurate descriptor than "protect and serve" in these cases (and, I imagine, much more generally).

The best way to rob a bank is to be a banker.

This is severely anecdotal: I know a few people who basically did this. They admitted one of their prime motivations for becoming a cop was being able to do things like speed, control others, take authority in situations where they wouldn't normally need it, etc.

you have to know the system before you can beat it.

Similar idea-> I think the only reason Ed. Snowden was able to get away / stay out of US prison was he had worked so long with CIA/NSA etc that he was very familiar with the tactics they would use to go after him, and he was able to take appropriate action to evade them.