Actually, I think a lot of people got invested in this story and trial because we started out looking for a missing little girl that the mother lead us to believe had been taken by the nanny.
Then the story started taking a new twist or turn daily with each new lie by Casey. We were fascinated with the bravado this mother showed in lying to the police about her place of employment and other lies.
So, in answer to your question, her color has nothing to do with this and you know it.
I still remember the "breaking news" that the remains of a small child had been found in the vicinity, and the followup that the "head was wrapped in duct tape".
If that scenario doesn't fuel national interest (and the Dick Tracy gene that lives amongst most of us), nothing does.