There are several MARTA bus stops within walking distance of his house. He could've had a Breeze card or cash, I guess. Buses will take you to the trains. There are also quite a few other neighborhoods within walking distance, and you are in Cobb County/OTP within just a few miles. (ITP = inside the 285 perimeter / OTP = outside the perimeter in ATL speak)
IMO, the answer to your last question is yes. Since he runs, I don't think he'd be opposed to traveling a good distance on foot. I mentioned some specific wooded areas before (namely Standing Peachtree Park), and @arta mentioned Crestlawn. Others have mentioned the rail yard. But in close proximity to his house, you also have: the old Bolton landfill, the water treatment plant, the old City of Atlanta incinerator (side note: super creepy), and most concerning to me for someone in crisis, the Chattahoochee River with several accessible bridges. This area is not nearly as densely populated as the rest of Atlanta, even though it's in town. There are huge areas to canvass.
Hope that helps!
Very helpful, thanks. Hopefully there are ongoing local searches in the areas you pointed out.
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