Before the outbreak, Gilroy worked alongside Rick and Shane at the Cynthiana Police Department. One morning, he was informing Rick about the drunk they had brought in the night before when Lori Grimes had called and told Rick that her water had broken. Rick had Gilroy call Dr. Stephens so that he could meet them at the hospital.
It is unknown what happened to Gilroy after the outbreak occurred. While Rick is riding into Atlanta, he rambled to the horse about the day he found out about Lori's water breaking, mentioning Gilroy.