Chandler (1971) – IMDb

Chandler: Directed by Paul Magwood. With Warren Oates, Leslie Caron, Alex Dreier, Mitchell Ryan. A hardboiled aging private eye is hired to find and protect a missing government witness sought after by the gangsters. The witness is a beautiful French woman and even the cops can’t be trusted. The case is tough, but so is Chandler.

https://www.imdb.com/title/tt0068356/