Then ... The investigators go to the 322 Club in search of the fisherman's unemployed son who might have had access to the murder weapon. They are reflected in the window of the venerable Speedy's, on the corner of Union Street and Montgomery atop Telegraph Hill (map). In the distance Union Street dips down then soars up to Russian Hill.
... and Now, next to Speedy's the so-called club entrance leads into an apartment house, address 303 - 311 Union Street - it never was a club in real life. On a trivia note, Speedy's finally closed down in 2008 after serving the neighborhood for 93 years; the site is currently a boutique, Acre/SF. Over the years Speedy's has appeared in several movies, as here in The House On Telegraph Hill in 1951.
Inside the club (presumably filmed in a studio) the barman denies seeing the suspect, even as he sneaks out the back door. But Andy spots him and the chase is on.
Then ... The back door is right behind him as the suspect bolts into a narrow street. Remember that the front entrance was on Telegraph Hill? ...