What if the death was accidental?
The problem in this case is that people assumed the death was intentional based, in part, upon the fact that this scenario of duct tape, chloroform, and driving around in a car for a month before dumping the remains in a swamp is something a crazy person would do.
I hate to break the news, but psychopaths see bodies as shells to be disposed of once the fun is done. Unless they are saving a souvenir, the body is the thing that ties them to the crime.
I propose that--if it is true that she drove around with the body in the trunk for a month--that it actually supports the theory that the death was unintentional.
It's not without precedent for people not to report a death because they can't accept the fact that their loved one is gone. I know that sounds bizarre, but is it really much different than say, people letting grandma live alone in her own filth and can barely cook her own meals because they can't accept the fact that she is no longer the strong vibrant mom that raised them as children? People sink into deep denial about things, and its possible that the need to hold onto the body outweighed any sense of justice that she might have.
And if she reported the child's death, they would take the body away. She would no longer see her child and she would have to be confronted with the stark reality that her child is dead.
Maybe she mummified the face with duct tape so she would not have to see the child's expressionless face.
And who knows? Maybe she disposed of the body in the swamp out of the same fear that they would take her away. She could have possibly wanted the body nearby to go visit when she liked, but hidden in a way that nobody should have been able to find it.
What bothers me is that psychopaths go back to doing their own thing as if nothing had happened. While she went out and partied, there were other signs that something just wasn't right. When people are under stress, they do odd things. And that's exactly what she did. She could have gone out and partied just to let people think that things were normal.