have taken you as far back as you can go, you want to begin to access the county records. There are many records of formerly enslaved African-Americans after the end of the Civil War in the south. There were many who purchased lands and recorded their deeds. They often mortgaged them and recorded the mortgage. And those who did own land frequently had a probate when they died.
Tax records, voting registration lists, militia lists - former slaves can be found in all these beginning in 1868/69. Court records are another good resource, though it's sometimes hard to find them indexed. A call to a genealogical society in the county or area your family resided in can often hook you up with a local black researcher who could tell you more about the local records. A membership in that society could be helpful. They often have websites and facebook pages now.
You may not find your subject individuals, but whether you do or not there may be clues that lead you to a former slave owner. And remember, not all African-Americans in the south were enslaved. There were often communities of free persons of color, and it's possible your subject family was not enslaved at all.
Once you find an owning family, the probate records are the first thing to search that might lend big dividends. Intestate estates, especially, often had the slaves inventoried along with the other personal property. In those inventories, the slaves were usually listed in their family groupings. Husband first, then wife, then children by age. There is often a bracket around the family group, with the appraisal amount listed for the family unit. At least this is the case in South Carolina, and I would suspect possibly in Georgia.
I recently had a happy surprise in the 1860 census, when I looked at the slave schedule I saw that slaves were also listed by family units in the one for my county. Names were not given, but age and sex allowed for nothing else. Again, this may not be true anywhere else, but it is something to watch for.
And if you find your subject was enslaved by a large plantation owner, check local and state repositories to see if those family descendants donated the family papers.
Watch for changing names of formerly enslaved people. at the end of the war. In my experience it happened more frequently than most realize. Check the neighbors closely, residential and naming patterns among the neighbors, any little clue at all can become of big importance.
Also check the county Genweb site, and the Genweb Archives for that county. You may not find your subject, but watch for potential owners, family naming patterns, all the things you watch for in any genealogical research.
You are certainly on the right track with Afrigeneas and Cyndi's List. Check Cyndi for your county to see what records might be available online, and what repositories you might find them in. Some are still in the county courthouses, some may have been moved to the state archives. Sometimes the state archives will have listings as to what county holdings they have, and what is still in the county. I don't know what is online at the Georgia Archives. Staff at the state archives are usually quite helpful and respond to phone calls or emails if they can.
Also just put your subject's name in quotations and google it. You never know. And you might google the surname and the county and state name.
Oh! Inquisitions. In the south they had Coroner's Inquisitions over unexpected deaths. I had an uncle, white, who died in similar circumstances to your guy. I always heard he fell out of a truck and busted his head and died. When I found the 1932 Inquisition Book, the report confirmed that was exactly how he died. It also stated he was drunk and driving the truck at the time.
Slave and freedmen research is very difficult, and others can likely help you more than I. But these ideas may help a little.
Wat