I don't practice in South Carolina but generally, there isn't much for an attorney to do unless you need a custody order or a court order to have a person turn your child over to you.
If the abduction was a crime, i.e., a stranger abduction or removal in violation of court ordered custody arrangements, your local law enforcement should be able to get a court order for the tax info.
I have included below a link to another parent's website on finding missing children.
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In addition to what Mr. Rich said, consider hiring a private investigator if the cops are falling short on finding the child.
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