Jake Randolph in "The Eternal Night" Pt. 193

"The sad thing is," Salem continued, "Sandy got the part in the movie that she and Lily auditioned for. She only came back up here to quit her job at The Devil's Den and then to get her things and move to Hollywood. She came by to see me the day she was killed. It was tragic."

So, Sandra probably was meeting Detective Lyman in the alley to tell him she was leaving town and wouldn't help him bring down the pornography ring.

So if Gertie and her gang are the ones that killed Sandra, they did it for nothing...