I believe she is guilty, the the law of the land says that you have to be proven guilty beyond reasonable doubt. There was no hard evidence showing her guilt so no matter what the jurors believed in their heart the law stated that they had to let her off. With regard to the reasonable doubt, they don't know when the girl was killed, how she was killed nor did anyone see her get killed. They seem like a strange family with many problems even before the death of this little girl.
This. The prosecution didn't have a confession, fingerprints, the cause of death or any witnesses to the baby's death/murder. Those are usually the types of things that can overcome jury doubts, according to someone on a tv show I watched earlier. They didn't have any of those things, so they couldn't get the convictions they were seeking.
Isn't it possible that the baby died in an accident (the words "neck breaking" were searched), then the grandfather and Casey decided to make it look like a kidnapping/murder? But the police unfortunately weren't tricked by the ploy, and charged Casey. They should have just called the police and reported the accident.
I don't know what happened, but Casey's tears and relief looked like those of an innocent person when the verdict was read. I don't think she killed her daughter.