DAYTON, Ohio (AP) - Detectives looking into the death of a month-old girl didn't at first consider that a microwave oven might have been used.

They knew the baby had been burned but were unsure how. The baby's mother, China Arnold, told investigators she had no idea what happened.

But on Friday, nearly three years to the day since the baby's death, Arnold was convicted of cooking her child in the microwave. The baby's DNA was found inside the microwave in Arnold's apartment, prosecutors said.

Prosecutors said Arnold intentionally put her baby in the microwave oven after a fight with her boyfriend.

Arnold was found guilty of aggravated murder and could be sentenced to death. The jury was scheduled to return Tuesday to begin a sentencing hearing.