Wonder what could have been the motive?
Money’s usually always the motive.
So the article says that he used to be their son-in-law, married to one of their daughters, and they had owned a business together, now defunct. My guess is that it’s either about some kind of debt from the business, and the dad was helping his daughter or had told him off and demanded payment. That, or a child custody issue, are my guesses.
The woman accomplice is probably his present girlfriend, and she wants da munnah, or to be out from under a child support or debt repayment order.