As if a pair of undies is enough to frame someone for murder

So if the detective retrieved the undies from his pants, it doesn't imply that he murdered Gloria. All it does is implies that he is a pervert. But I have to admit the killer's attempt at framing the main character for murder was pretty lame. What he forgot to do was call the cops just Gloria murder was suspected. That way the cops would arrived and found him by the body. Perhaps if someone remade this there would have at least been a cell phone involved