The Iguana with the Tongue of Fire (1971)

In Dublin, the acid-scarred, razor-slashed corpse of a young woman is discovered in the boot of the Swiss Ambassador's limousine. The Ambassador, his family and employees all become immediate suspects. Faced with the problem of diplomatic immunity, the police officer in charge of the case brings in John Norton, an ex-Inspector known for his brutal methods, to carry out an "unoffical" investigation. While Norton develops a relationship with the Ambassdor's attractive daughter, several more gruesome murders occur...