I'd previously seen this 1972 giallo by Alberto De Martino from an old VHS source, and dubbed into English, so it was a welcome opportunity to see it again for the first time in a clean, widescreen, Italian dub with English fansubs.
Savalas is a suitably menacing, near-silent presence, recalling his role in Bava's Lisa and the Devil, while Heywood passes muster in the Frightened Woman role more usually assigned to an Edwige Fenech, Florinda Bolkan, Carroll Baker or Dagmar Lassander.
The theme of the unreliability of memory is, of course, a staple of the filone -- one thinks of The Girl Who Knew too Much, The Bird with the Crystal Plumage and Lizard in a Woman's Skin before this, and of Footprints on the Moon and The Man Without Memory a couple of years afterwards.
While not reaching the heights of these points of comparison, The Killer on the Phone is nevertheless a solidly put together production, benefiting in particular from a lush Stelvio Cipriani score and attractive cinematography from Aristide Massaccessi.
De Martino tries to inject a bit of style into proceedings, but his contributions are more hit and miss. The slow-motion lyrical flashback scenes as Eleanor recovers her previously repressed memories whilst under the influence of a truth drug are a bit over the top in that post Elvira Madigan way. The director is on surer footing when it comes to such staples of the form as the fetishisation of weaponry and black gloves; the close-ups of eyes; the shock zooms and, yes, plenty of product placement for Justerini & Brooks.
The theatre space provides the location for an effective finale that sees 'the curtain descend, everything end' or 'bring the house down' in an almost literal way for at least one of the dramatis personae; to say more would spoil things.