I have notice the last few days when i wa sfighting a guard that when i kill it, it will stuck itself in the fase when it dies.
Then it will just stay in the die fase and disapear after a good while. While it is like this no other guard will spawn.
And u don't get xp from it when it gets stuck.
http://images.akamai.steamusercontent.com/ugc/398925305482013024/8DF7BBF5BE8F93079FDB8A5D1674798221A4A302/