"My money is on either he was physically abusive to wife or sexually molesting daughter(s). Thoughts?"
I'll bet he that he used to leave the toilet seat up, or
He always left his underware on the floor, or
He put the toilet paper on the roller thing wrong, or
all three.
From a Yahoo! News story a little while ago:
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" ...
Tennessee Bureau of Investigation agent John Mehr said authorities know the motive for the killing, but he would not disclose it. He said police did not believe it was infidelity, but he would not comment on whether Mary Winkler had accused her husband of abuse. Court papers offered no hint of a motive."