Exactly. People keep forgetting about the dog. Shouting set the dog off? How about multiple shots from a .45 automatic? (If you are to believe the Alex/Lori/Tylee story).
My personal opinion is that everything told to LE, including by Tylee, was a fabrication. I think Alex's truck was parked out of sight and Charles pulled into the driveway, walked inside and was confronted at gunpoint by Alex and Lori and ordered to surrender his wallet, rental car key fob, and phone. Lori and Tylee then hustled JJ and the dog through the garage into the Kia and drove off. Alex shot Charles (probably with a suppressor on the .45), and staged the crime scene by retrieving his truck, doing a bit of cleaning, and fetching the bat. Cops arrive, stories are told, happy-happy all around. Except for poor Charles.
Again, in my opinion, Chad and Lori started worrying that Tylee wasn't going to stick to the story. They arranged for her to be handed off to person or persons unknown at Yellowstone, and she refused to go, so they brought her back and killed her (or killed her on the way back). JJ became unmanageable and so they killed him. No more humanity than a pit viper between the two of them.