What proof do you have that there was an exchange of money (or some other money equivalent) between the seller and your dad?

This sounds like you are being scammed. If you were interacting with a minor or an actual undercover police officer posing as a minor, you, likely,...

You need an attorney ASAP. Whether you have a claim in worker's comp, medical malpractice or against a third party who may have caused your injury...

This is not enough information. Is there pending litigation? Meaning have you filed a suit against them or they against you that is currently...