It is confirmed that Bob Stookey, a former army medic and a citizen of woodbury will be featured in Season 4 this coming October, So where do you think he came from before he will join Rick's group as he is not seen with Tyreese's school bus.

My Speculation: He is a part of the Woodbury army that attacked the prison but never returned to the caravan ( maybe lost in the tombs or in the forest like Jody but never encounter Carl and Hershel)

Just leave your thoughts in the comments if you have better speculation than mine

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