Petty criminals and small time crooks are often the ones that make life hardest for people, especially the poor who live in the neighborhoods where these guys operate.
When I lived in Wilmington, DE (a pretty run down post-industrial city), our favorite restaurant was run by an elderly Indian couple. But it was in a terrible neighborhood, and one day their house was broken into. These sweet, hard-working people were violated, and by who? Not some kingpin. By some "small time crook." Should he not be prosecuted to the full extent of the law?
Would cover your case.
Keep in mind that we have the precedent of innocent unless proven guilty in the US, so the suspected drug kingpin, terrorist, or serial killer is just as innocent as the suspected bubble-gum thief.
Our system, while admittedly imperfect, prioritizes protecting the innocent over punishing the guilty (obviously it's more complicated than that, but that's the core)
1-http://www.nolo.com/legal-encyclopedia/content/rico-act.html
It makes sense that if some harm keeps getting committed then someone should do something about it. But if that's not the case, then it does not justify any action from the government. Like in Mexico the drug war, sure go after the major drug kingpins using totalitarian systems. But to put this on petty criminals, small time crooks, etc. that's just horrible.