This is one of seven B budget Michael Shayne movies 20th Century-Fox produced in the 1940s. The same character had previously been featured in several novels and a weekly radio program, and would be made into a TV series in the 1950s.
If you look at the opening credits Henry Daniell's name is misspelled. His last name only has one l in it. It should have 2 l's.
American Film Institute Catalog of Feature Films (1941-1950), erroneously reverses the roles of Ben Carter and Mantan Moreland. IMDb lists them correctly. Ben is Sam, Mantan is Rusty.
Strangely, Ben Carter is billed fifth in the opening credits and his sometimes partner Mantan Moreland not at all, even though they have roughly equal screen time and Moreland was much better known. In the end credits, Carter is still fifth and Moreland is at the bottom, his name misspelled as "Manton."