Originally Posted by DjSap

I think you mean prosecutors. There aren't that many DA's to begin with. Basically prosecutors usually are people who weren't good enough in law school to be recruited by criminal defense firms. Thus they opt to go for the second path which is to be a prosecutor for a few years and then switch over to private practice once you have some valuable skills to bring to a CD firm.

Not sure where you got the cops thing from, while there are cops who become CD lawyers the number of former prosecutors is waaay higher.