 George MurphyInspector James 'Jim' Belden | Inspector James 'Jim' Belden |
 Finlay CurrieProfessor Albert Kafer | Professor Albert Kafer |
 Virginia GilmoreMillie / Teresa Zalenko | Millie / Teresa Zalenko |
 Karl StepanekAlexi Laschenkov / Gregory Anders | Alexi Laschenkov / Gregory Anders |
 Louisa HortonMrs. Elaine Wilben | Mrs. Elaine Wilben |
 Peter CapellChris Zalenko / Gino | Chris Zalenko / Gino |
| BBruno WickLuther Danzig | Luther Danzig |
| VVilma KurerMrs. Rita Foss | Mrs. Rita Foss |
| AAnn ThomasPhiladelphia Suspect | Philadelphia Suspect |
 George Roy HillNicholas Wilben | Nicholas Wilben |
| KKarl WeberFBI Agent Charlie Reynolds | FBI Agent Charlie Reynolds |
| MMichael GarrettMichael Dorndoff aka Frank Torrance | Michael Dorndoff aka Frank Torrance |
| LLotte Palfi AndorAnna Kafer | Anna Kafer |
| EErnest GravesRobert Martin | Robert Martin |
| RRobert CarrollBoldany | Boldany |
 Wolfgang ZilzerAugust Helmuth | August Helmuth |
| BBradford HattonHarry Mason | Harry Mason |
 Rosemary PettitMrs. Martin | Mrs. Martin |
| EEva CondonLandlady | Landlady |
 Steve MitchellSamson | Samson |
| JJohn FarrellTaxi Driver (uncredited) | Taxi Driver (uncredited) |
 Nancy HaleMrs. Belden (uncredited) | Mrs. Belden (uncredited) |
| WWestbrook Van VoorhisNarrator (voice) (uncredited) | Narrator (voice) (uncredited) |
 Mary YoungOld Lady (uncredited) | Old Lady (uncredited) |
| SSuzanne MoultonSherry Belden (uncredited) | Sherry Belden (uncredited) |
