GALVESTON, Texas, March 14 (UPI) -- The trial of a Texas man accused of scorching his infant daughter in a microwave oven began with conflicting stories about how the child was injured.

Joshua Mauldin, 20, has pleaded not guilty by reason of insanity to a charge of injury to a child, The Daily News in Galveston reported.

The charge arose from Mauldin's eventual admission to investigators that he placed his 2-month-old daughter in a microwave and turned it on for about 10 seconds while alone with her in a hotel room in May. The admission came days after the child had suffered second- and third-degree burns, requiring extensive skin grafts, the newspaper said.

The story of the burns changed according to whom Maudlin and his wife, Eva, spoke, witnesses testified Thursday. An investigating officer said the parents initially said the child was sunburned. A police detective and child services officer said they were told she was scalded.

The prosecutor said Mauldin was aware enough to lock the room's door during the attack.

Defense attorney Sam Cammack countered his client had a history of mental-health problems and was not responsible for his actions.