I agree with everything you've said. But if KW was a serious suspect, would the lead detective still be working the case part time?
If KW has any connection to this crime its to be a thorn in the side of the family. Possibly hoping that the Sherman family will pay him off or erase his lawsuit debt in order to shut him up.
I doubt if he has much of an impact on the family. They have attorneys to handle thorns. And he is not much of a thorn. Maybe a little pricker is what we call the prickers on Canadian thistle.