How does infection choose the next round's zombie?

How does infection choose the next round’s zombie? I made a gametype where there is one zombie and 5 rounds in a game. Everybody has one life per round. I keep noticing that after each round it seems to chose the last man standing as the next round’s zombie. Is it supposed to be random? If not, does anyone know how I can make it random?

> How does infection choose the next round’s zombie? I made a gametype where there is one zombie and 5 rounds in a game. Everybody has one life per round. I keep noticing that after each round it seems to chose the last man standing as the next round’s zombie. Is it supposed to be random? If not, does anyone know how I can make it random?

Everything is completely random, like bloom.