Richard Conte is dubbed by another actor in the English language version.
The flashback sequences set in a mental asylum recycle footage from La casa delle mele mature (1971), an earlier film produced by director Angelo Pannacciò
The titular exorcist does not show up until about 15 minutes before end of movie, though he has some voiceover prior to that.
Italian censorship visa # 66762 delivered on 26 June 1975.