Need to track him down since with $6M you can easily disappear & change your identity.
Case won't help to get the investors money back.
There is no need to track him down. Several people already know his current address and that is all that is required to have legal documents served on him but there is no need to do anything like that because once the Police are involved they will not let him off the hook. They will arrest him, they will charge him with various counts of theft and fraud and he will go to jail.
No they won't.
Things are not working like that in scotland. Police kinda careless when it comes to bitcoin offenses. As sad as it sounds, this is the truth.