Little is known about Jim's life before the zombie apocalypse. He was once an auto mechanic from Atlanta who only managed to escape by abandoning his family to the undead, something that has haunted him ever since. He eventually met up with other survivors and became a part of their camp, putting his mechanical skills to use by helping maintain Dale's RV and the other vehicles.
In the episode "Vatos", Jim is seen digging holes on the hilltop near the quarry. The rest of the group become concerned as he does not explain why he is digging and he is digging alone in triple digit heat. When confronted about it, he becomes hostile but soon collapses from sunstroke. After being tied to a tree and cooled off with cold water, he apologises to the rest of the group and explains he can't remember why he was digging. However, he remembers after the camp is attacked by zombies. The holes were supposed to be graves for the fallen.
During the attack on the camp, Jim is bitten by a zombie around the stomach. He tries to hide the wound but Jacqui calls him out, alerting the rest of the group. A debate erupts concerning what is to be done with him since he will eventually turn into a zombie, but the group pack up and leave the quarry before reaching a decision. Meanwhile, Jim becomes increasingly ill and while on the road he asks Rick and the others to let him out and leave him behind. In the end, the group honours Jim's last request and after a tearful farewell they leave him under a tree by the roadside. It is safe to assume that Jim eventually died from his infection and reanimated, though he is never seen again.