I hear ya. I think that in these murder cases we've seen that before. Implausible lies.
Sometimes it may be because they're used to lying and manipulating others and getting away with it. So they think they will be believed here. Like casey anthony. Her story was so wild they asked her if she what any mental health issues or hospitalization or if she was on something. Remember that?
Is that kind of what you're thinking of?
Those types often have a history of lying to charm people or get away with things and it usually starts with parents who refuse to believe anything bad about their little angels. So the kids grow up feeling confident about their abilities to lie, even when their lies seem transparent.
I could see that being a possibility here.
But that differs from compulsive lying which is more lying for attention, I believe or out of compulsion. Rather than to manipulate. Their lies tend to cast them in a positive light.
Compulsive Lying