Whats the easyest way to kill George on Call of the dead?

I used the upgraded olmpia about maybe 5 or 6 clips on him, an 2 full death machines. He was flashing yellow, so idk if he was almost dead or not. an thats the last trophy i need to get on this but its pretty hard. i herd an upgraded scavenger can kill him but i tryed it one time an it didnt work. An dont say the upgraded V-r11, the human gun, will kill him cuz it only puts him out for like a round or 2. So can u please tell me whats the easyest way to kill him.