Possible Clues:

• One who saw it happen
• Detective faked news -- it's in Observer
• They saw one newt-eye tossed in by sneaky sorceress, to begin with
• Yes, seen rarely to possess intelligence — I can vouch for it
• Supplier of trial testimony, perhaps
• Person at the scene perhaps sees win yet is upset
• View from The Observer and The Spectator
• Testimony source, perhaps
• Gloomy tree having special quality in curious sense, one observes
• Heard I could be wisest to hide name of person at the scene