Hello,
In case you are still in need of vanishing villager scenarios, I just had one 

.  I had an adept researcher find the graveyard, then go and bury the only dead body there was.  When he was done, and leaving the graveyard, I switched his preferred skill to "healing".  I knew I would need another good healer since the best one I had was getting old.  I then dragged him to the cactus where he promptly disappeared.  My village population went down by one.  Then when I checked my stats it said that 2 villagers had been buried.  Sure enough, when I went back to the graveyard, there were two headstones.  
I'm still early in the game, with only 93 hours played.  My max # of villagrs is 12.  I'm playing on a Tungsten E.