Later, after he was arrested and in prison, he finally told investigators that the girls were alive when he drove them to the site. He smothered Cece first, dropped her in the tank, and then Bella asked him if he was going to do the same thing to her that he did to Cece. He said he didn't remember if he answered but that her last words were, "No, Daddy!"
When they interrogated him before his arrest, after he finally admitted he killed Shanann and dropped the girls bodies into the tanks, he casually described how he opened the lids and dropped them, one at a time in two separate tanks. Bella didn't fit as well so he had to push her body through. He said one tank was almost empty and the other was more full. When they asked him how he knew he said he could tell by the amount of time before he heard each one "splash."
He talked about all this calmly until they asked if there was any way his daughters could have been alive before he dropped them. He blurted out, "No, God no!"