Prosecutors said during opening statements Thursday that Mauldin was trying to get Ana to stop crying, but defense attorney Sam Cammack III said he was a "loving, caring father" who was trying to protect her.
Just before the infant was harmed in that hotel room in May, Mauldin started hallucinating, thinking about a strip club, feeling a white hot burning sensation in his stomach and then feeling like "mud was running up his body and consuming him," Cammack said.
"He places her in the microwave and says, 'I saw what was happening but I couldn't do anything about it.' Then he stops and says, 'Oh my goodness. My child is in the microwave.' He pulls her out," Cammack said.
Cammack described Mauldin as very religious. He said his client has been hearing voices since age 10 and has been "wracked" by psychosis, schizophrenia and other disorders that have gone untreated.
Mauldin's wife, Eva, has blamed Satan for her husband's actions, saying the devil disapproved of his efforts to become a preacher. His wife was not in the courtroom but some of his family members were.
Galveston County prosecutor Xochitl Vandiver told jurors Mauldin was not insane and hurt the baby because he couldn't stop her from crying.
"He feels agitated. He just wants to get out of there. The baby is fussy," Vandiver said. "In the middle of hurting his child, he stopped, went to the hotel room door and he locked it. And that was to prevent his wife who was downstairs from coming in. And that shows you he knows what he was doing was wrong."
Mauldin lied to authorities about what happened to his daughter, telling different stories that never matched the child's severe injuries, she said.
Galveston police officer John Rutherford testified Thursday that Mauldin first told him the infant had been sunburned that day as he and his family had moved from his hometown of Warren, Ark., to Galveston, located about 50 miles southeast of Houston. Rutherford said Mauldin later told him Ana was injured after he tripped and spilled hot water on her.
Nicholas Baudains, a former investigator with Child Protective Services, testified that Mauldin confessed to him four days after the infant was injured.
"He put her in the microwave. She didn't fit so he had to force her in," said Baudains, who became emotional on the witness stand.
Baudains told jurors that Mauldin's family didn't tell him about any mental health problems the Arkansas man might have had.
But he said that Mauldin told him that just before injuring his child, he felt like he was burning up and that his hands were turning into mud.
During Rutherford's testimony, prosecutors showed jurors photographs of the infant's injuries. The photos showed how the infant's left cheek, ear, hand and shoulder were severely burned, turned bright red and began to peel and blister.
Mauldin cried, and at least two jurors seemed to get emotional as the photos were shown.
Prosecutors said part of Ana's left ear had to be amputated and the skin on her left hand melted.
She suffered second and third degree burns, according to testimony, and required two skin grafts. She was hospitalized for 11 days.
CPS officials say Ana, whose first birthday was last week, is still receiving treatment but is doing well and living with relatives in Texas.
Testimony in Mauldin's trial is set to resume on Friday.
If convicted of the felony charge, Mauldin faces a sentencing range from probation to life in prison. He has been jailed since his arrest.
Mauldin has pleaded not guilty by reason of insanity. The state's definition of insanity is that a severe mental illness prevents someone who is committing a crime from knowing that it is wrong.
Prosecutors have said they plan to challenge the insanity defense by highlighting Mauldin's criminal history, including stealing a handgun from his baby sitter when he was 13 and being discharged from the Army after a court-martial conviction for stealing another soldier's laptop.
Another trial is scheduled for April, when CPS will try to terminate the Mauldins' parental rights.