On two occassions, I've encountered ghosts who were waiting for someone just before they (the ghosts) were killed. They didn't understand that they were dead, or at least they were confused about whether or not they were still in a body, and they thought they needed to stay where they were until the people they were waiting for showed up. I've encountered quite a few ghosts over the years, and my experience has been that when things are sufficiently explained to them, they usually go where they belong.