Betrayal at House on the Hill - Scenario 50 - Do the Clue Tokens drop when a character dies?
Page 12 of the rule book says:


  Many haunts put one or more item tokens in the house, which have special rules for their use. Unless the haunt says otherwise, item tokens can be traded, dropped, or stolen just like item and omen cards.


I'm not sure why they felt it necessary to mention that they can be stolen or traded in the haunt, since that would already be the case according the above rule. However, it does not say they cannot be dropped, therefore they can. If they can be dropped, then I would assume they are also dropped when a character dies.