Punishment options range from probation to life in prison, prosecutor Jason Parrish said earlier.
The prosecution said the child’s injuries were intentionally inflicted.
Photographs of the child’s feet, which suffered second degree burns, show no signs of splashing, common for accidental scaling situations, according to prosecutors.
Tyler Police Detective Michelle Brock testified the evidence was inconsistent with the Walkers’ account of the incident, and the explanation changed during subsequent interviews.
In the initial version given to police, Mrs. Walker said she was folding clothes and heard the children screaming in the master bathroom, but she had trouble reaching them because the door was locked and had to call her husband for assistance.
In a second version, Mrs. Walker said she was fixing breakfast as her husband was lying on the couch when they heard screams coming from the bathroom. The girl and her then 3-year-old brother entered the living room with the child crying that her feet hurt.
The detective accused Mrs. Walker of lying to cover for her husband.
Defense attorney Cameron Castleberry said Friday the Walkers gave differing accounts of what happened because their grandson had turned on the water and they were trying to protect him.
Dr. Scott Lawrence, an East Texas Medical Center emergency room physician, testified he believed the girl’s injuries were accidental and consistent with someone walking around in hot water.
He said the injuries were possibly caused as the children were playing in the bathroom and one of them turned on the hot water while the girl was in the tub.
When she realized the water was becoming hot, she tried to climb out and encountered difficulties maneuvering past the sliding door, he theorized.