The situation you describe is the precise reason that the United States has the RICO act[1]. Prove that someone is involved in a scumbag organization (insert legalese for "scumbag" here)and they're guilty just like the person who committed the crime.

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