Was the boy mute all along? Or did Dracula make him mute?
At the first of the movie, the boy rides in on his bike and enters the church. Did he not speak to someone as he rode in? After his discovery in the bell tower, he is heard screaming at least 3 times. Later, when the monsignor arrives and questions him, he appears pale and dark circles around his eyes as if Dracula has been feeding off him. And he can't speak.
"Cum Grano Salis"