What do you mean "he had no choice"?
Was there another person we don't know about holding a gun to his head?
What irresistible force made him take the body of one of his little girls out of the truck, climb a 25 foot oil tank and force the child's body into an 8 inch opening?
Then that same person with a gun or irresistible force gave him "no choice" but to climb down, get the other girl, climb up the second tank and force his other daughter's body into the 8 inch hatch?
He had lots of choices.
He could have chosen to put them all together or better yet, not to hide them at all.
He could have chosen to stop part way through the 4o minute drive with the bodies in the truck and realized what he was doing was wrong and taken them to a hospital or police station.
He could have left them all in the house and chosen to drive himself to Mexico, fleeing like the coward he is.
Or, last of all, and I really wish he has chosen this-- he could have chosen NOT to murder his family. He had about 4 minutes during which he strangled the first victim where he could have realized what he was doing and stopped. He could have still saved that life. He could have walked away and gotten a divorce. At no point in time did he have "no choice".
He made ALL the choices.
MOO.
(Sorry for the rant.)