I don’t know. My experience was mostly with drug cases, that could go to either federal or state court. We noticed if the case wasn’t very strong, thee feds would decline prosecution and the state prosecutors would take it up. (Which in our state usually meant much more reasonable sentences). Some cases, like organized crime, are really only well suited for federal prosecution most of the time. You hear of some lower level defendants in multi-defendant trial sometimes getting off, but the main target is typically convicted.