Prosecutors allege that Jessica Tata had hot oil cooking on a stove at her day care when she left the children alone to go shopping at a nearby Target store. But Tata's defense attorneys have told jurors she didn't intend to harm the children, who ranged in age from 16 months to 3 years old, and that the February 2011 fire was not caused by anything their client did.
Tata, 24, is charged with four counts of felony murder but is currently being tried in the death of 16-month-old Elias Castillo. She faces up to life in prison if convicted.
Electrical engineer Richard Bonyata, testifying for Tata, told jurors he believes a switch that would have been used to turn on the burner in question was in the off position at the time of the blaze.
Because of that, he said, "You would have to consider all other competent ignition sources ... and completely eliminate everything else."
Bonyata said the evidence pointed to the refrigerator as a possible source, citing heavy damage to the refrigerator's doors, as well as to the cabinets and woodwork next to and above the refrigerator.
In addition to the possibly malfunctioning refrigerator, Tata's attorneys have previously suggested that the burner switch might have malfunctioned. They have alluded to problems with other stoves with similar switches, such as their burners turning on by themselves or unexpectedly jumping from low to high heat.
Last week, David Reiter, a forensic electrical engineer who testified for prosecutors, said he examined the stove and found no mechanical or electrical failures. Reiter said he determined one of the burners had been on at the time of the fire and found no evidence indicating a problem with the stove's switches.
A former Target manager previously told jurors that while Tata was at the store, she remembered during a conversation that she had left the stove burner on.
Convincing jurors that Tata was responsible for leaving the burner on before allegedly leaving the children alone could be important for prosecutors in getting a felony murder conviction.
Prosecutors do not need to show she intended to harm the children, only that the deaths occurred because her actions put them in danger. Under Texas law, a person can be convicted of felony murder if he or she committed an underlying felony that led to the death.
"The defense's battle is like going up a steep incline with a tricycle," said KTRK legal analyst Joel Androphy. "There's been so much evidence in this case so far about her neglect, her reckless behavior. She's told people that she left the stove on."
Androphy believes Tata will be found guilty of felony murder if jurors believe she left the stove on and started the fire. Otherwise, he says Tata could walk free or serve just a short sentence.
"The stove is what elevates this case from a reckless endangerment case from two to 20 years, to a felony murder, with five to life," Androphy said. "So it all revolves around the stove."
Along with the murder counts, Tata was indicted on three counts of abandoning a child and two counts of reckless injury to a child.
The Associated Press contributed to this report.