Jack, I'm not sure about the novella, but in the first full-length novel I'm pretty sure Ender murdered two other kids - one on the transport up to the school, another in a bathroom years later. Ender was unaware that he had actually killed either kid. For his watchers, it validated their choice of him. In the novel from the Bean perspective, I don't think these incidents come up, but I really need to re-read both.