I just re-listened to CW's CBI interviews, and those of his co-workers. If I have this correctly, he got to Cervi 319 at 6:45, and the other co-workers like McCoy, Melissa, and another one got there at 7:30. He knew they were on the way. He claims in the CBI interviews that he took about 20-30 minutes to dig her grave. I think he just ran out of time due to the airline delay. And that there was some plan like ThePoet is outlining to get rid of the Lexus. Why did he park the Lexus outside, on the street, so many days/nights, per the neighbor?
I agree with you that it doesn't make any difference, and that he will never tell. Even if he did tell, like the DA said, who would know if it was a lie or not.
There will be books a plenty. I just think that it's mostly impossible to diagnose these A holes who do it just once after a lifetime of being a non-offensive nebbish.
One other thing I wanted to mention is that NK claims to have participated in zero sites, she mentions a few, including Facebook and "IG" which she says she specifically did not use. IMO a person who does not use instagram would never call it IG. Along with her other BS like "I hardly knew him", she frequently spilled the beans on herself because of her motor mouth.