If they don't have any money, as they say, you can't get blood from a stone. But you can put in a claim in bankruptcy, and try to assert that the debt is non-dischargeable. (Without knowing the specific terms of the divorce judgment, I cannot be sure if that's the case.) If the debt is not discharged, after the automatic stay is lifted from the bankruptcy proceeding you can seek to enforce it through the bankruptcy court.
It's impossible to know from what you posted if a crime occurred. If you believe so, talk to your divorce lawyer or make a police report.

