I have now heard two different news bureaus report that the DNA has been badly contaminated. However, I do believe they can separate it.
One media stated directly that the contaminated sample is the one under her nails. They said that it was contaminated by a scalpel used in a previous test. I believe there are at least 3 different samples.
It's probable cause, and probable cause is quite easy to demonstrate. In this case, Karr has made statements that constitute probable cause. All the phony experts yammering away on TV and radio keep making it seem like probable cause must be strong evidence of guilt. No way. Probable cause has a very weak threshhold, and the vast majority of judges pretty much rubber stamp whatever the cops or DA gives them when seeking a warrant on probable cause.