Murder by Contract (1958)
aka
Der Tod kommt auf leisen Sohlen
Claude (Edwards) one day decides he's had enough of being a regular Joe earning regular Joe wages. He decides to become a hit man, and after enacting a few clinical kills he works his way into the confidence of the mysterious Mr. Brink. This earns him a "big hit" in Los Angeles, where he is to snuff out the main witness in a big upcoming trial. All is going well until he finds out the target is a woman, so where once Claude was calm and assured, he now becomes irritable and irked...... (IMDB Spikeopath)