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Given the mother was into art, could the murder be linked to her?

I didn't think so - that seemed to be unrelated

It seems like the murderer is sending messages in the form of sculpture and it could be the reason the murderer chose that form since his wife was into sculpting. Could it be someone like her teacher or a classmate of Derek's wife?

I did wonder if it was connected to the mother's death in that accident that was mentioned.

if the killer knew the family and had maybe been in the house, he probably saw the sculptures so he made the killing fit the interest of the family.

It seems like it could be related because why even mention his wife liked sculpture if there's no connection. Or it could be a red herring.

I can't see what any link would be: too early to do anything but guess.