Why is the necklace so important? The detectives didn't even take it into evidence until months later, right? Again, if he took it off her that night/early morning, why wouldn't he get rid of it, hide it, flush it down the toilet? It was in the guest room where his mom was staying, right?
I think the state made a HUGE deal of 2 things - the necklace and the dress. The dress turned out to be nothing. He didn't even wash it that morning (imo based on the opinion of SBI, deodorant stains, oily stain). So what that he forgot what she was wearing that night initially.
The necklace too. Why didn't he pitch it if he had to know it would incriminate him?
Because it was worth $3,000!
You can produce 5,000 pictures of her wearing the necklace, but I think it is very hard to jump from "she never took it off" to "this proves he killed her". It's similar to the argument that NC "never" ran in the Fielding Dr area. Don't think any of these "never" arguments can be strong enough to pass the "reasonable doubt" test.
The prosecution needs just one little piece of "homerun" evidence catching BC if not in the act, then lying about his alibi. I'm still hoping they have computer evidence that shows something. This guy has got to have left a trail someplace.