In that article it says that a family friend... John Sean Adams... found them and then further down it says that the owner of the house, who lives in New York, asked John, a family member to check on the family as the owner had been trying to contact the renters and hadn't been able to contact them. So John is their son but doesn't live at home. I'll bet there are two adults and three children. How awful to go in and find your family all murdered. Something a person would never get out of their head.
They are really keeping this one quiet. The news just gave the barest of details like dead in their basement. Oh, and it is believed to be homicides and not homicides and suicide.