Murder In Trinidad
Seton I. Miller (screenplay)
Nigel Bruce as Bertram Lynch, Heather Angel as Joan Cassell, Victor Jory as Howard Sutter, Murray Kinnell as Colonel Cassell, J. Carrol Naish as Duval
"A seemingly slow-witted detective arrives in the Colony to take over the investigation of stolen Brazilian diamonds and is tangled in series of murders with a dagger, that has on its handle a snake and crescent insignia, as the weapon." - IMDB
Note: based on the book .