Regarding the question of how one person could remove three people from the home.
Let's suppose that the perp was "double-crossed" (real or imagined) by one of the victims in a business deal. Let's suppose that the perp went to the house between 10-11PM to demand money from Alvin (who had made public that he was liquidating and leaving the country). Alvin was at home with his wife and grandson, and would not want to expose them to a business confrontation. Perhaps he suggested that they step outside, sit in his truck to discuss it, or perhaps the perp asked Alvin to sit in his truck to discuss it. That way, the grandmother and grandson are separated from the problem, and Alvin is already in the truck. Alvin could have been attacked in a vehicle. The perp could then enter the home, catch the grandmother off guard, attack her and the child.
The drag marks from the side of the house to the parking pad could be blood belonging to the grandmother, and that could explain why the Amber Alert specifically said that the child could be with his grandfather. That was stated prior to an analysis of Alvin's truck and the green truck.
All three victims could have been put in Alvin's truck, or the green truck, and removed from the scene. The truck was seen more than once in the area of the crime scene, so there could have been a second or third trip to clean up the scene, with the last image of the green truck taken at dawn as it was leaving the property for the last time (nothing in the back of the truck).
Police were seen collecting evidence, like bedding, from landfill sights. It's possible that bedding was used to cover up the victims in the back of the truck and that it was seen on earlier photos of the green truck.
