Here's the cover from the DVD of one of the Jerry Cotton movies starring American actor George Nader, THE MURDERERS CLUB OF BROOKLYN. There were several of these made in the Sixties, with titles like DEATH IN A RED JAGUAR and THE VIOLIN CASE MURDERS. They appear to have been filmed in the U.S., but with German casts and crews, other than Nader in the lead role. I've never seen any of them, but if I could find a DVD with English subtitles, I'd probably give it a chance. I can sort of read German, but understanding it when spoken is beyond my feeble linguistic abilities.