It's been five years to the day that Hannah Overton was convicted of murder we've been following the emotional and legal twists of this bizarre story ever -- It began with something so seemingly... See More
It's been five years to the day that Hannah Overton was convicted of murder we've been following the emotional and legal twists of this bizarre story ever -- It began with something so seemingly innocent that all moms can relate to a forty year old throwing a temper tantrum. But was it -- or sign of something much more dangerous and what was behind the parents split second decision not to call 911. But now stunning new allegations about the woman who prosecuted the case could set Hannah Overton free. -- -- -- -- -- And all Andrew bird ever wanted was a fan to call his own. All -- and Larry Overton ever wanted was a home filled with children I one and three. And she won -- six and so -- -- five now. So I guess she's winning. The -- Corpus -- couple fell in love his young missionaries. They started a family and always talked of adopting when the Overton -- Andrew in 2006. It seemed like the perfect fit. Playing in their -- -- -- and that didn't have them has until I can drumming and then Hillenbrand. Forty year old Andrew had been warned to -- fanning two and placed in Foster care at the age of two do you abuse and neglect. His Foster mother attended the same churches -- -- so Andrew got to know the kids through Sunday school. My girlfriend. -- interest payments for Trevor mommy and then he can end Trevor family. At the time -- and Larry had more biological children -- -- -- Isabelle six LE fines and Sebastian to. The young family -- off -- modest salary from the landscape lighting business and made it work she home schools. He built furniture even though Hanna became pregnant with -- fifth child they volunteered to become Andrews for have. Pray as it was very exciting to be able to get an outlet for so many who -- -- -- The pastor Ron carver and his wife movie noticed an immediate change in -- if you -- around skirts. And do his colleagues. With his Brothers and sisters. And who would tag along handlers keep all the time. And every time Iverson and we just couldn't breath behind and -- -- on this team. But within a few weeks of Andrew moving into their home -- and -- say they began to see some odd behavior. And -- and then he winds -- According to sing and then he winds and hand stealing up the other agents plates when indeed -- getting upset when their cameras over. Describe -- when you caught him eating things inappropriate things. Anything hair anything and he found he would -- -- nothing else and we need -- -- -- that I can out of the trash can despite concerns the Overton hoped Andrews habits would improve with time and I had also been home. And by name I can't start caring and an adopted children will have problems so you give him a break -- apple. But -- behavior never changed according to the over tense -- -- Worse obsessive eating. Excessive tantrums. Just four months after Andrew moved in the unthinkable happens when he was going -- ten from kind of -- and nineteen -- -- done. Then -- stumbled to the floor complained of being cold and started shaking. -- says she suspected the flu and oust her husband to come help she wrapped Andrew and blankets. And -- He's still -- -- Deals with some say it wasn't until an hour and a half later that they saw no improvement in his condition this was no clue you in preening and congestion. And -- and pan am like gurgling sound in the -- and he wins. And moaning. They put Andrew in the car and raced to the hospital and why didn't you call 911. -- was an option but I felt like thank you get him to the hospital quicker than 911. Then -- Overton say Andrew's condition suddenly went from bad to worse. I think the iron fence that -- -- -- here something. And I and -- parent and hard. When he arrived at the clinic Andrew's condition. It's critical blood tests revealed Andrew had salt poisoning with the sodium level almost double the norm. Among the highest levels ever reported. Doctor Edgar Cortez treated -- that day -- Never seen as soon. Opinion on if you take -- at a level faster than your body can remove it. So -- level will go can cause brain swelled convulsions and then eventually death. -- told doctors Andrew -- condensed soup with this data -- creole seasoning -- to bulls he wanted more but instead -- says she offered him -- zipping up like -- of water with a few sprinkles of the seasoning. And sell my -- was that I would calm him down and p.'s hand and it give them -- -- like LeBron went. Giving him a -- and -- meaning more fame. But that story didn't -- up to the medical staff. One doctor calculated it would take at least 23 teaspoons to get Andrew sodium -- that -- And there was something else suspicious unexplained bruises and scratches on Andrew's body and medical staff had obviously. Been alerted SARS something said hey we need the police here. Corpus Christi police detective Michael -- got the call that day as their son lay in a coma -- and Larry were taken here to police headquarters for questioning. -- truly important. How he had a wet. Here and -- -- -- he's. I think here. Well -- Concerned about these things missing. She said was chilling in just won't take two steps and say was called -- -- -- -- You think they're. Who you calling -- -- people. We work for me that's what we're trying to. And just society where Sharon. Emergency thing. Who I have pretty common. Financing. Idea I let them. You're seeing -- watching this child diet and you don't do anything. You do that I don't understand that. The toxic levels of sodium -- and his brain to swell his ordinance to shut them. On October 3 2006 the day after he was admitted to the hospital. -- -- don't mind. How did you learn this it. I'm cleaned Intel that we couldn't come back from the hospital Sunday. We can. Can tell my mom and my step dad and I -- trip there. -- -- -- -- There was some reason Hannah and Larry were banned from Andrews bedside to investigators the over -- worked grieving parents -- the prime suspects. At Dover teens home on conditions. Andrews mattress outside his favorite Spider-Man bed sheets burnt on the grill. A camera pointed at the bare plywood -- -- Since Raymond. Maybe there's something. What was going on in the old Virginia home that day.
This transcript has been automatically generated and may not be 100% accurate.