The data already exists, or will exist when such distributions are caught -- is it unethical to use it?

In the extreme, to produce better models, your business would eventually be incentivized to create new data... but if you limit yourself to the usage of data collected as a byproduct of stopping criminal activities, it's not clear to me what the morality case should be.

A historical example might be the nazi human experiments -- the experiments themselves were horrendous, but now that they've been done and we have the results, is it unethical to use that as the basis for further, ethical, research? That is, would it be unethical for me to read the outcomes?