From your link:
Grant County detectives said the injury on Theresa Bergman's head is consistent with a shovel strike.
A GCSO deputy spoke with the Bergman's daughter on Sept. 19. According to documents, she told detectives that her parents were married for approximately 36 years and that her mother had recently asked Charles Bergman for a separation. Their daughter told detectives her father "became very depressed and contemplated suicide since Theresa's request to separate."
Oh man... apparently Theresa's son was supposed to pick her up from the airport and bring her to his house to get her car but plans changed to Charles picking her up.
It looks like a premeditated murder. MOO.