[cyncooper]

It could be that any trace evidence was destroyed by the environment she was left in. Some evidence was just lost by her condition. So evidence may have existed and been lost naturally (they had to cut off her whole nail to do the scraping). Nicole Simpson's nails didn't have OJ's DNA and I remember at that trial the specialists explained you really have to dig.

[juzcuz]

-Evidence lost by condition-

Yes, that is true. In fact Tomsovic worried about a heavy dew changing the crime scene. Not only was he worried about heavy dew, but rain (on the day she was found). He said it had last rained in that area on the 17th. He also said his team got on their hands and knees and searched all around and under where her body was, looking for trace..
DNA evidence could have been lost naturally around nail tips, hands, arms, etc. Anyway, tiny fibers existed under her nails even if they had to remove the nails to get to them. It stands to reason if she gripped an arm, there would have been imbedded DNA stuff there as well.