Typically, scammers use fake names and entirely fake contact information. Are these scammers people whom you have actually met, or were they just folks you were only in contact with by electronic means?
Thank you. If this is a real person and you have actual contact information for him, then you would have legal remedies that you should be able to exercise. I'm therefore going to opt out of this question and move it to our French Law category where a lawyer in France can give you an idea of your rights and how you can go forward with them.
It may take a while for a moderator to move this to the correct category, so please be patient.
I've read the above conversation with Zoey-JD. If you have the name and contact of the person the only thing you need to do is file an official complaint with the police in Nice, or anywhere else in France. You can do it directly or by instructing a lawyer to do so on your behalf.
You will need: