Hannah Overton, 34, is serving life without the possibility of parole at the Murray Unit, a maximum-security women’s prison near Waco, Texas.

Her crime: capital murder for salt poisoning by omission or failure to act.

The often-crusading Texas Monthly magazine picks up in its January issue on whether life imprisonment of Hannah Overton for the death of her four-year old foster child, Andrew Burd, on Oct. 3, 2006, was an injustice. The San Antonio Express News and ABC’s 20/20 have also recently questioned the justice of Overton’s conviction.

At the center of the case is something that is said to be so rare that the typical Emergency Room physician will never have to deal with it: salt poisoning.  In the four years since she was locked up at Murray, new evidence has emerged that in turn has brought one of the top experts on salt poisoning of children into the case.

Common salt is poison only if consumed in large enough quantities. For example, it would probably take 40 teaspoons of salt to kill an adult. Both salt poisoning and dehydration can cause hypernatremia, which means critical care doctors must know how to distinguish between the two.

Dr. Michael Moritz, clinical director of pediatric nephrology at Children’s Hospital in Pittsburg, is a specialist in children’s kidney diseases. According to Texas Monthly, he published a seminal paper on salt poisoning in 2007.

Moritz was brought in when Cynthia Orr, Overton’s appellate attorney discovered the records of Burd’s stomach contents not previously disclosed to the defense. They showed salt levels were not elevated with the boy arrived at the urgent care clinic.

In his earlier research, Moritz found children who accidentally ingest too much salt often fit a narrow profile, living in the foster system or being from abusive homes, and suffering from a disorder known as pica.

While Burd was depicted by Texas prosecutors as being a “normal” four-year-old boy, TM’s Pamela Colloff provides extensive biographical details on the Overtons and the foster boy they wanted to adopt that tell otherwise. Andrew’s adoption supervisor suspected the boy had pica, an eating disorder.

It involves eating largely non-nutritive substances, sometime including clay or chalk or other materials.

Moritz said the stomach contents report is evidence no murder was committed.  “If someone was trying to murder Andrew, they would have restrained him and prevented him from drinking water, ” Moritz’s affidavit says.  “The very dilute gastric sodium contents suggest…that he had unrestricted access to water.”

Moritz goes on to say: “There is not a single piece of evidence which suggests that Hannah Overton salt-poisoned Andrew.”  He says it is far more likely Andrew “salt-poisoned himself.”

Currently again on appeal to the Texas Court of Criminal Appeals, Overton’s conviction was made possible by jury instructions.  It made no difference whether Overton forced the boy to eat salt or he did it on his own and she failed to get him timely medical attention.

The sentence for capital murder in Texas is either the death penalty or life imprisonment without parole. In this case, the Corpus Christi prosecutors did not seek the death penalty.

Note: Texas Monthly offers limited access with free registration, but requires subscription for full access.