On June 22, 1850, he was, however, found guilty of theft by a French Court and sentenced "in absentia" to 10 years imprisonment. His friend, the archaeologist and writer Prosper Mérimée (1803–1870), argued in his favor and was prosecuted for this. Mérimée, the author among other stories and plays of "Carmen", had been convinced of Libri's innocence when the Count had told him that the missing French books and manuscripts must have been forgeries since the ones he had were the originals.