ared Gurman, a 26-year-old from New York, shot his girlfriend Jessica Gelderman, 27, early on Monday morning.
He fired a round into her back with a rifle, piercing her lung and diaphragm and shattering her ribs.
Ms Gelderman survived the shooting but was left with serious injuries.
Detective Raymond Cote told NBC that Gurman was arguing with his girlfriend of three and a half years over whether the world could be overrun by zombies.
"I just know that he felt very adamant that there could be some type of military mishap that would result in some sort of virus or something being released that could cause terrible things to happen," Detective Cote said.