CIRCUS OF FEAR (1966)

 This one is an interesting watch since it blends a few different genre-types together. It starts out as a typical heist-film and then ends up in a circus where people are getting bumped-off in a very giallo-esque way. Christopher Lee, wearing a black hood for most of the movie, is one of the main suspects in these murders. Klaus Kinski plays one of the armored-car robbers. The circus scenes are mostly lifted from 1960's CIRCUS OF HORRORS. The one main complaint I have with this film is that it's marketed as a horror film when it's actually a mystery based on those old Edgar Wallace novels. Once you get past this though it's passable. AKA PSYCHO-CIRCUS and CIRCUS OF TERROR

In full color despite what this trailer shows:

The German title of THE MYSTERY OF THE SILVER TRIANGLE gives you way more of a clue to it's mystery movie  elements: