I have been playing the game for awhile now. And in one room the people keep saying there is a dead person. But all the people are alive in my shelter/vault. There has been other people that came in the vault but they got killed. I'm not sure if it's one of those intruders that is dead in the room. But I somehow I can't find the dead person. Help! Thanks!

You may have to destroy the room and rebuild it. Sometimes it will glitch and if there are no dead dwellers in your dweller list then there's no way to select the body to remove it.