GALVESTON, Texas -- The foster mother of a baby burned in a microwave testified on Tuesday in the punishment phase of the trial of a man convicted of severely injuring his daughter, KPRC Local 2 reported.

Joshua Mauldin, 20, was found guilty of felony injury to a child Tuesday morning. He put his 2-month-old daughter, Ana Murphy, in a Galveston motel microwave and turned it on for 10 to 20 seconds in May.

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Slideshow: See Pictures Of Baby Burned In Microwave

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Mauldin faces a sentencing range from probation to 99 years in prison. Prosecutors are asking for the maximum sentence.

He pleaded not guilty by reason of insanity.

During the punishment phase, Heather Croxton tearfully described how she cares for and loves Ana.

"I can only imagine how that would feel -- to know that the man who was supposed to take care of her did this to her," she said.

She described Ana's wounds, and the painful process to clean them and administer medication. Ana has silicone adhesives on her facial burns.

"The scar tissue and skin grafts -- as she grows, they become tight. They have to be released. So, she will always need to go to Shriners," Croxton said. "She can't spread her fingers out, so she has like a ball."

Croxton also showed recent pictures of Ana, who smiled and appeared happy.

Croxton, who has three boys, said she hopes to adopt Ana.

She is torn about telling the girl how she received her injuries.

"The whole world knows. I fear that she would find out anyways and would feel betrayed by us," Croxton said. "So, I'm not sure. I don't see how we can not tell her. She's going to have the scars for the rest of her life."

Defense attorneys said Mauldin loves his daughter but had a psychotic episode. Doctors testified that Mauldin had a history of mental illness and was diagnosed with a major depressive disorder three weeks before the baby was hurt.

Mauldin's mother pleaded for probation for her son and blamed herself.

"I feel like I have ruined this child's life. If it hadn't been for my mistakes, Joshua wouldn't be in this position," Joanie Mauldin said.

A jail psychiatrist who evaluated Mauldin also testified. He described how Mauldin chewed into his own wrist soon after his arrest. Mauldin was put on an anti-psychotic medication.

Both sides gave brief closing arguments. Jurors began deliberating punishment shortly after 3:15 p.m.

Mauldin was expelled from school at 16 years old for setting a locker on fire. He was also discharged from the Army for stealing a computer.

Ana, who recently turned 1 year old, has undergone several surgeries. She faces more surgeries and will probably have future medical problems due to her second- and third-degree burns to her hand, face, ear and shoulder, according to doctors.

She has no contact with her parents or paternal grandmother.

Ana's biological mother was subpoenaed to testify for the defense during the trial, but did not show up. She could face charges for leaving her baby alone with her husband, whom she tried to have committed to a psychiatric hospital one month before.