AI, not human, because the actual incidence rate for a lot of crimes is much much higher than most people realise, including for extremely severe cases:
• Statistically speaking I think it's something like most Americans commit three felonies per day*, but that's probably mostly drugs which IMO should be liberalised anyway.
• For an example of extremely serious crimes, and again statistically speaking, your first day in highschool, your first class on that day, you likely met someone who had been sexually assaulted by a family member.
Increasing a human police force to the scale needed to catch all crimes is theoretically possible (the Stasi basically operated at this scale even if they only thing they cared about was sedition) but is a terrible idea.
If all crimes keep their current penalties, a fully automated surveillance state bankrupts everyone almost immediately.
Note: I'm not suggesting this is a good future. I don't think it's a stable equilibrium, I think there's too high a risk of a leadership using such a surveillance capability to hold power, and they may even not care too much about non-state crimes once they do seize power, so this could easily become Stasi 2.0 or worse.
* Or the mean felonies per day is 3, which is a very different claim. I've not read the book: https://en.wikipedia.org/wiki/Harvey_Silverglate