Historically, torture was far more likely to be used on accusers and witnesses than presumed perpetrators. The idea is that if you're tasked with some sort of policing role and can't possibly figure out who is in the wrong, you just beat up both the accuser and the alleged perp. Chinese justice in the imperial era worked pretty much the same way: criminal punishment was neither explicitly retaliative nor restorative in intent. The basic dynamics is that this hopefully makes it less likely for people to lie, since no one sane would want to risk being beat up unless they had an actual grievance and no other way of addressing it.