We want them to pay and it may be difficult to do so from behind the bars. We need Chinese lawyers to make contact with them. I think criminal option is the last resort when everything else fails.
Just some thoughts:
If you have ever dealt with some Chinese officials regarding a fraud case, you know that this is - to say it politely - difficult. Often it turns out that they find fraudsters, get money from them and let them go. Happened more than once in cases I was involved in as a researcher.
The same is true with lawyers. You HAVE to know who you are dealing with, and the best is often someone who is not from the area.
Also consider hiring a private investigator. This is risky, though, for the Chinese officials don't like other people doing the research. However, there are some who come out from governmental agencies and know how to find evidence, persons and hiding their own tracks at the same time.
Just my 2 cents.