Judging from what I read on wikipedia:

-She is clearly guilty of child neglect, making her more likely to be guilty of either murder or manslaughter

-The body is too far gone to see how the child died, and there are no witnesses or convincing dna evidence

-Overall, there is very little evidence that points in favour of either murder or manslaughter to the exclusion of the other

-Manslaughter has a higher prior probability than murder (especially when swimming pools are involved, which are responsible for about 25% of all deaths for children that age from what I've read)

-Therefore I find that probability (manslaughter or other cause) > probability (murder)

-Legally speaking, she can not be convicted of murder beyond reasonable doubt

-however, the probability of her being guilty of murder is still around 20%

-Legally speaking, she can not be convicted of manslaughter beyond reasonable doubt

-however, the probability of her being guilty of manslaughter is still around 65%