Sadly, it’s too late now, but it really would have been better to hire a good child care provider and just let him be a stay at home dad for things like driving, housework, shopping, etc., or just being there as a supportive parent in the background.
Also if the mom had had a camera on the garage and driveway so she could check remotely if he was sticking to her directive to not leave them in the car.
It’s just so sad that the 2 girls now have a dead sister, a father headed to trial and incarceration, a grieving mother, and all the travel and fun spoiled. This case has really hit hard for me.