Almost nothing is known about O'Toole's life before or as the outbreak began except that he is a retired teacher.
Sometime after the outbreak, O'Toole met up with survivors from the "Tent City". Lilly mentions that he is one of the few people not brought in from the scavenging run by Chad Bingham.
It is unknown what happened to him after the camp was overrun by walkers and engulfed by flames. Lilly's group states that it was very unlikely that anyone survived. It is also possible that he could have been one of the sixteen survivors killed during the second walker attack on the camp.