Unfortunately, there is no cut and dried technique. A person who has handled or had plenty of experience working with wolves is your best bet.
Features differentiating the two are very subtle.
Further, genetics testing is still undefinitive as far as I'm aware. At least, genetics work will not hold up in court. That leaves you with the first option, which in a place like the Carolinas, doesn't leave you with much for an option. Sorry, but differentiating wolf vs wolfxdog or dog is still exceedingly difficult.