 Although Tenebrae was an Italian production , most of the cast spoke their dialogue in English to increase the film 's chances of success in United States . For domestic audiences , the film was dubbed into Italian . The English @-@ language dub retained Franciosa 's , Saxon 's and Steiner 's natural voices . However , Nicolodi 's voice was dubbed by Theresa Russell , Giuliano Gemma 's was dubbed by David Graham , and most of the female voices were dubbed by Adrienne Posta . Michele <unk> – frequent Argento collaborator , second assistant director on Tenebrae and later a noted director in his own right – acted alongside Robin 's in the second flashback scene . Another of Argento 's collaborators , Fulvio <unk> cameoed as a hotel porter . In common with several other Argento films , close @-@ ups of the killer 's gloved hands were Argento 's own . In the film 's Italian @-@ language dub , Argento also provided the opening voice @-@ over , reading aloud descriptions of murderous actions from Neal 's fictitious novel , Tenebrae . 
