Knights Templar History: Veritas vos liberabit

One of the weakest points in Raymond Khoury's "The Last Templar" is the use of the phrase Veritas vos liberabit (The truth will set you free). This Bible verse from John 8 is enigmatically presented as one of the Templar's mottos, because it can be supposedly found on some Templar castle in France (Chateau de Blanchefort, to be precise). I was unable to find any references to this inscription. I mean, if every Templar castle had this inscription prominently displayed... According to the novel, the markings are there, in plain sight. Why can't I find any pictures anywhere?

P.S.

According to one of the comments, the name of the castle is Chateau Blanquefort. The book clearly states Blanchefort. Perhaps it is a minor issue, because I would be happy enough to see any Templar structure with the inscription "Veritas vos liberabit."