I want him in prison for a year, and I would pay any reasonable amount of money to make that happen. But I have no idea how to arrange that, and none of my Khmer or foreign friends in Cambodia have an idea either. Of course I would try to stay out of the picture so he doesn't know which of his victims put him in prison.
I think I have done everything I can do, now can only wait for him to make a mistake (i.e. contact any of the people I have alerted to the issue, or appear on hotel security camera without mask, or steal from someone who is better connected than I).