I think Tyler James Young's answer does fairly well, but I'd also like to suggest "emerged" as another alternative to came. Since you ask for an alternative that is suitable for beginners, "emerged" may collocate nicely with some learners' native language(s).
"Came" is used since it doesn't need to be further explained (by who? how? etc), and I think "emerged" works quite well in this regard too. It also sounds more natural than "arrived" or "appeared".
Using the passive (as suggested in a comment) could potentially cause difficulties for beginners, and so I would avoid it. However, if you think it could be a viable option, try "The latest possible lead was revealed".