Old thriller movie - store robbery

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Hello, I am trying to remember for quite some tim now from which movie is the scene where the robber enters the store and has the clerk at gunpoint. Clerk does not look up and holds his head down all the time while talking to the robber. At some point, after he gave all the money, he tells the robber that he didn't look at his face and can not identify him, but he gets killed anyway. I think this robber is also main villain in the movie, some serial killer or something.
I can not remember anything from the movie but this scene, I know it is the long shot and not too many info shared from my side, but is worth trying at least.
I know it is an old movie, I watched it when I was kid, maybe even 25-30 years ago. It really bugs me, the fact I can not remember.
Thank you.*

Might not be an easy one to narrow down - do you have no other info at all .... like whether this was in colour or black & white or even what language it was in? If English language any idea where it was set - America, UK, somewhere else?

Hello, I am 99% sure it is color movie, in english and takes place in America. Unfortunately, that scene is only thing I remember. Will try to come up with some other details, but not sure if I will be able to remember. Thanks a lot for reaching out and looking forward to any suggestions from your side.

I have definitely seen this movie. But it was a long time ago -- in the 1970s or 1980s, I think.
I have bookmarked this page and will come back to it from time to time, in the hope that I may eventually remember some details, such as who played the detective pursuing the murderer.

Thank you very much. Hope you will remember, since I am apparently hopeless

Any memories?

Not really. As I recall, my father and I watched this movie from the start, while my younger brother wandered in after it had been on for a while. I am pretty sure this was during the late 1970s and that the movie was broadcast by a TV network and not a local station. But I have not remembered any details of the movie itself.

I saw this movie during my 3rd year college film intro in 2013. I fell in love with everything it encapsulated. They always tell you that back then motion pictures were like such scenes and I believe it. To be there, to sit through the overture in a cinema where movie stars have been and just absorb everything would be amazing. I'm not saying we don't have great movies now, we do. There's just something very romantic about movies like this.

I am not sure that this was a movie; it might have been an episode of Police Story. I suggest looking through the episode summaries at IMDb (https://www.imdb.com/title/tt0069620/) to see if you can find a match.