Lightwizard wrote:Kudos to you.  Yes, it's "American Madness."
How did you crack it?
 
Funny you should ask.  I was pretty sure about my identification of Robert Emmett O'Connor, so I scrolled down his list of credits in IMDb.  Since he played two kinds of roles -- cops and detectives (pretty broad range there) -- I looked for any role where he played a plainclothes detective.  His character in "American Madness" is listed as "Inspector," so I followed the link and it showed the cover of the VHS edition, which looks like this:

Walter Huston's unruly coiffure on the VHS cover is the same as in the picture you posted.  Thus, I shouted, "Eureka!"
But I never would have guessed that the guy on the right was Pat O'Brien.  It doesn't look like him at all.
OK, maybe this will pose a challenge.  It's probably a publicity still, but it shows the two main characters in the movie.