Yes. It's my solemn vow that I even the playing field a bit further. You can allow the others to know they will be able to pinpoint if a victim was afflicted by a Ghost possession.

[ He is bounded by his rules after all. ]

As with any case, there can next be a perfect murder. If you and the others are able to dissect the evidence - much as you did last trial - and partner it with the new assistance I'm offering you - it should be quite easy to narrow pool of suspects.