former nueces county prosecutor, sandra eastwood. >> andrew had an enraged mother who didn't -- i don'thim the way that she loved her own biological children. >> reporter: the prosecution's theory was that hannah turned abusive, ultimately forcing him to consume a toxic dose of this creole seasoning. detectives even used the overtons' own children to build a case against them. investigators believed these interviews with an 8-year-old isaac, obtained exclusively by "20/20," seem to prove there were unusual forms of punishment. >> you get pepper? what does that mean? >> it's like spicy and it hurts your mouth. we have a security camera that's facing his bed. every night, my mom watches it until we see him fall asleep. >> why? >> to make sure he doesn't do bad things. >> it's a little odd. you adopt a child and you watch the child through a security camera because he's always in the bed. all these things started like adding up, like pieces in a puzzle. >> reporter: the odd circumstances found at the overton home were detailed in these arrest warrants, describing a virtual torture chamber.