Although if someone had seen any reason to question him, Charles might have been able to tell them about the strain between Beth and Bryce Or at least a little about it. Though it's pretty likely he wouldn't have really wanted to, since the few times you see him he strikes you as someone who wants to mind his own business.
(I always sympathize with characters like Charles - people are always making sure I hear all about their personal lives, and everyone else's.)

True. That is a good point.

Thanks. It's fun talking Columbo.

Yes, but you're looking at it from a "viewer" point of view.

Remember, there were no witnesses to what she said or did, so she could say she said she had a gun, etc.