Drug addicts associate with each other. Police who aren’t lazy or corrupted can develop trees of association, even on paper. That provides a way to start and eventually get it all done. It would also be helpful, if they stopped shooing clean informants away to protect criminals who are local favorite sons/daughters.
Ah, ok.
So you want “trees of association” and a system of carefully monitoring who associates & engages in exactly what behavior with whom, & informants informing on everyone eh?
Sounds like a communist police state is what you want.