#Cedrika: according to the Journal de Quebec the site where the skull was found had been searched previously:
Le secteur où les ossements de Cédrika Provencher ont été trouvés avait été fouillé après sa disparition
It is unclear whether the police conducted the search or whether it was supervised by the local search and rescue group, Quebec Secours. This means one of three things: 1. They did a poor job searching the first time. 2. She was originally well hid. 3. She wasn't there originally.
They probably did a poor job searching the first time but I'll leave it to other journalists and the Sûreté du Québec to find proof of that.