Translate the following English sentence to French:
"The third way is to strengthen and improve the role of the ombudsman, mainly by giving him easier access to all the documents needed in order to conduct an efficient investigation."
Enfin, le troisième moyen est le renforcement et l' amélioration du rôle du médiateur, notamment en lui facilitant l' accès à tous les documents qui rendent plus efficace le déroulement des enquêtes.