I am also in favor of catching violent criminals. And as such I join you in the downvote fest. Of course, no one puts forth a cogent argument about why catching violent criminals with this technology is bad. Can it be abused? Yes. Was it abused here? No. Luckily, we live in a democracy where we make the rules. If we want a policy that law enforcement can't buy these systems, make that the law. If we want a policy where law enforcement can't use these systems in any capacity, then make that the law.