I think even though the case is clear, there are some facts that prohibit the filing of a fraud case:
Silvia apparently signed an LPOA - and if that paper does not clearly state anything about limitation of loss to 20%, it will be tough to argue in court. Scammers and fraudsters know EXACTLY what to do and HOW.
The attempt to ask a crook to come to the forum and argue his side of the case is about as obsolete as it can get.
There is in my opinion only ONE way left: Silvia, file a criminal complaint in whatever appropriate jurisdiction(s), send the FBI a written statement of what you experienced and make them aware of that Miami address, include all names that were related to this address (seems it wasn't the first time).
Now, I have my serious doubts that ANYONE is doing ANYTHING against an Israeli..... They know it and use it to their advantage.