Watched this movie recently for the first time and really liked it. Just wondering, was Shelby at the appartment when Diane was shot? Didn't he know throughout the movie that Laura was not the person that was killed? I may have missed something.
shareNo plot hole. Yes, Shelby was there and knew that Diane was shot.
What he DIDN'T expect that Diane would be mistaken for Laura.
He explains this to Detective McPherson when McPherson follows him to Laura's cottage in the woods.
In his confusion, he told McPherson that he didn't know what to do, and wanted to keep Laura's name out of it (scandal of him being at Laura's with another woman).