I'm not watching the episode tonight (I imagine I'll do so tomorrow when I eat lunch, after I've gotten some stuff done for school), but there seems to generally be an "incubation" period of sorts after a person is bitten, dies, and becomes a zombie, so I'd guess that the guy you're referring to got bit, hanged himself, and then zombies got to him shortly thereafter - before his body had time to be reanimated as a zombie.
Think back to Jim at the end of season one. He was bitten during the zombie attack on the camp, but didn't die in that attack. However, we could see the effects that being bitten was having on him - intense fever, hallucinations, etc. Presumably he would've ultimately died from the virus, and then turned after death. I'm assuming something similar had happened to Jenner's wife, Candace / TS-19.
Oh, and you got the names of the brothers mixed up. Norman Reedus is portraying Daryl, while Michael Rooker was/is Merle.