I contacted our local Pirate party about the topic, because they don’t have anything related to crime prevention vs. privacy in their programe.
The general attitude in the German PP back in the days when I kept track (it's been a while) was "stop slurping data you'll never need from people not even under investigation, hire more investigators and do actual police work instead".
A good example here is the arrest of the founder of silk road: No computers were hacked in the process. They put a team of investigators on it who found OPSEC failures which are kinda unavoidable when you're up against a state-level actor. All without mass surveillance, only thing needed was good ole police work.
Also, side note, "prevention" and "enforcement" should never be used in the same sentence. The best crime prevention is social policy, not law enforcement. Next in line, swift and fair sentences in juvenile courts, time is very crucial there to form an association in still malleable minds. Next in line, sentences that forego retribution and focus on reintegration.