Your comment about the two brothers is exactly echoed in the book as the last sentence is:

"The two brothers may yet have more to tell us"

There's a comment that better, uncontaminated, DNA results could be obtained by drilling into a tooth but Rosalie David says that would be destructive and there's no actuall suggestion that it will be done.

I'm sure you'll find more than I've quickly gleened when you've got the book and I could easily have missed something as I was just flicking through.