 After Argento had experimented with pure supernatural horror with 1977 's Suspiria and 1980 's Inferno , Tenebrae represented the filmmaker 's return to the giallo horror subgenre , which he had helped popularize in the 1970s . Argento was inspired by a series of incidents which saw an obsessed fan telephone the director to criticise him for the damaging psychological effects of his previous work . The telephone calls culminated in death threats towards Argento , who channelled the experience into the writing of Tenebrae . The director also wanted to explore the senselessness of killings he had witnessed and heard about while staying in Los Angeles in 1980 , and his feeling at the time that true horror came from those who wanted " to kill for nothing " . 
