Death Knocks Twice
When private detective Bob Martin looking for a stolen diamond necklace, he also has a clever serial killer on the trail ...
| Actor | Role |
|---|---|
 Dean ReedBob Martin | Bob Martin |
 Fabio TestiFrancesco di Villaverde | Francesco di Villaverde |
 Ini AssmannEllen Kent | Ellen Kent |
 Leon AskinPeppe Mangano | Peppe Mangano |
 Werner PetersCharly Hollmann | Charly Hollmann |
 Riccardo GarroneArmando Locatelli | Armando Locatelli |
 Mario BregaRiccardo | Riccardo |
 Hélène ChanelAngela | Angela |
 Femi BenussiLois Simmons | Lois Simmons |
 Renato BaldiniLionel Simmons | Lionel Simmons |
 Teodoro CorràRinaldo | Rinaldo |
| LLanfranco CobianchiNot listed | Not listed |
 Tom FelleghyBerry | Berry |
 Nadja TillerMaria di Villaverde | Maria di Villaverde |
 Anita EkbergSophia Ferretti | Sophia Ferretti |
 Adolfo Celi"der Professor" | "der Professor" |
| MMarlies PetersenBabsie | Babsie |
| BBruno ArièCharly's Henchman | Charly's Henchman |
| AAntonietta Fiorito(credit only) | (credit only) |