Quoting from “Rennes-le-Chateau: Its Mysteries and Secrets” by Lionel and Patricia Fanthorpe, page 158 (1991):

“The Captier brothers’ great grandfather was Saunière’s bellringer, and it was he who discovered the mysterious little glass vial hidden in the secret compartment in the old balustrade which can now be seen in the museum. But, as always with Rennes-le-Château, not only is there some evidence that this balustrade and could not possibly have contained anything at all, but also that it could well be a reproduction installed in Saunière’s time!”

The story seems to have been first committed to writing in 1985 in Corbu & Captier’s book “L’Héritage de l’abbé Saunière”.

Parchments hidden in churches – sounds like something from a Gothic Ghost Story by Montague Rhodes James more than real history!