Rialto Film produced a cycle of films in a uniquely West German style of crime thriller known as the
kriminalfilme or
krimis. Originally based in Denmark, Rialto Film made a series of these films, starting with
Der Frosch mit der Maske (1959) and
Der rote Kreis (1960) which were aimed at the German film market and were successes in the country's box office. Rialto created a German part of their company that was a subdivision of
Constantin Film that would focus on the developing and releasing these films. A reviewer of the film in
Variety commented on the
krimi trend in their review of
Mark of the Tortoise in 1964, saying that under the supervision of
Horst Wendlandt of Rialto, the company had released 16
krimis in the last four years and "nearly all of them made money."
Mark of the Tortoise was based on the novel
Pay or Die by the British author
James Hadley Chase.
Variety had announced the film beginning production by February 12, 1964 in Hamburg.
Mark of the Tortoise was shot at Real-Film-Studios and on location in London and
Trieste.
Variety reported that it was made for about $375,000. ==Release and reception==