If "they" are both the planters of the rootkit (taking over the computer) and the ones claiming to be wronged, looking for recompense, doesn't this create an unreconcilable conflict of interest as well as a worthless chain of custody for evidence of any wrongdoing? What would stop them from simply taking over computers, planting evidence and profitting (extorting) hugely?

I would think that once my computer spends any length of time not under my direct and exclusive control, I would no longer be solely liable for any actions that may have been taken with it. There would be huge doubt, no?