My theory: 95 year-old Hackman's 63-year-old wife developed a terminal illness. Seeing no viable way of perpetuating their lives together in any reasonable way, they opted to take their own lives and that of the dog.
NOTE: I am not a trained criminologist. I just pretend to be one on the internet sometimes.
[ Attachment Invalid Or Does Not Exist ]
[ Attachment Invalid Or Does Not Exist ]