Does george romero spawn back after you kill him in the call of the dead zombies?

Me and my friends were playing zombies like right now basically and we are really burnt out at the fact that we killed george romero and he spawned right after the next round. So we don't know if we did it right or if that is suppose to happen because i thought he was suppose to disappear for ever after you killed him. I just wanted to know if anyone knew if he was suppose to spawn back after you killed him.