IMHO:
He's not a local, everyone in the area knows everyone.
The tattoo is pretty bad, but not a prison tat. The fact they are still looking for ID tells me there is no DNA, or Prints, or other information (other tattoos?) which would be in the NCIC, so the person has not been arrested of a serious crime.
It also seems that no one has reported the person missing, so it's likely the person was not married or close to his family.
Blunt force trauma, and using the tattoo for recognition? Could be blow to the face or just floating in the lake for a while and they didnt want to publish that image, notice the image with the tattoo there are several cuts.
The Date 2-14-92 is interesting, back to the tattoo being bad... could be the tattoo artist transposed 92 and 29, in reference to the Valentines day event. Most likely its just a coincidence though.
Assuming the dog did die in 92 looking in doberman forums and hoping for some animal clinic registry records seems fruitless.
If someone can get access to AKC records for that year they might be able to pull up something if the dog was documented pure bred and registered.
Kerr lake is a record fishing spot, it draws in people from all over. Since they didn't find a boat either he was tossed over one of the many bridges or thrown off a boat. Capone may be a popular name for dobermans, though it could indicate some wish to be a gangster. Perhaps he (excuse the pun) got in over his head. The proximity to interstate 85 and 95 would make the lake a good spot for anyone from Atlanta to NYC to make a dropoff.
Its possible the lack of a missing persons report indicates the person was homeless. It seems that no one is looking for him. Not many transients bother to stop in the area, much less reside there.
my thoughts:
He likely had little to no money. If so, he thought he was going to get into the drug business and failed. Perhaps he was on a boating trip and mad a pass and some ones old lady. Maybe he was a very bad person and tried to commit a crime against one of the locals who delt him in. He could be the victom of an as of yet unknown killer.
Because of the rural nature of the area I doubt he would travel there for suicide, though on a wild tangent he jumped off a bridge for fun and someone stole his car.
Basically, all we have to work on is a very old tattoo of a dog, and without more information no one will know.