I want to share something that I don't think most people realize:
When a Child Welfare Agency is involved in a high profile case like this, the agency cannot say anything while the family can say whatever they want. I am pointing this out not to defend the agency, but to say that I can promise you we know very little of the true story.
I work for a Child Welfare Agency and we had a high profile tragedy awhile back. The families involved took to the media with their claims and those claims were not true. The agency could not say anything. To this day, the public does not know the truth and to this day, the family members repeat the lies. This event demonstrated to me how little of the truth we know by what comes out of the mouths of the media or the families.
Very few people are 100% good or 100% evil and trying to pigeonhole either of the parents in this case causes problems. CPS is flawed, however you look at it. But who holds the blame? Everyone (mom, dad, maternal grandparents, paternal grandparents, aunts, friends, CPS, everyone) to some degree, but that is a hard answer to live with.