An Alabama grandmother is charged with capital murder in the death of her nine-year-old granddaughter, who was forced to run until she collapsed and died.

A prosecutor calls Joyce Hardin Garrard, 59, a "drill sergeant from hell," who forced the little girl to run for two hours as punishment for lying about candy.

Garrard's attorneys argue that the child died because of other health problems and medical malpractice, not anything Garrard did.

With final jury selection set to start this week, Judge Andrew Napolitano explained on "America's News Headquarters" that the crux of this case is experts disagreeing with each other.

Judge Nap noted that Savannah's father, Robert Hardin, filed a malpractice suit blaming his daughter's death on mistakes made at Gadsden Regional Medical Center.

Claims made in that lawsuit - specifically that medical workers failed to properly treat the girl for low sodium levels after her collapse - are similar to the defense's arguments.

Judge Nap explained that in Alabama the defendant must prove the affirmative defense, in this case calling expert witnesses to testify on Garrard's behalf that it was the hospital's fault, not her's.

"The issue is, did this running cause her death? Or did something else cause her death?" Judge Nap said, noting that Garrard could face the death penalty if convicted.

Watch more above and see Judge Nap share further insight on the Chris Kyle trial in the clip below.