DAYTON, Ohio — An Ohio woman convicted of killing her month-old baby daughter in a microwave oven was spared the death penalty and sentenced Friday to life in prison without parole.

Montgomery County Common Pleas Judge Mary Wiseman sentenced China Arnold, 31, of Dayton, who psychologists testified showed no signs of serious mental illness. Arnold declined to make a statement during her sentencing.

Arnold was convicted last week of aggravated murder by the same jury that recommended her punishment. Jurors deliberated about six hours Thursday and Friday.

Prosecutors say Arnold intentionally put 28-day-old Paris Talley in a microwave and turned it on after a fight with her boyfriend. The couple had argued over whether the boyfriend was the infant’s biological father.

Defense attorney Jon Paul Rion argued that the evidence pointed as much to the boyfriend as it did to the child’s mother, who Mr. Rion said was drunk at the time.

After Friday’s hearing, mr. Rion told the Dayton Daily News he would appeal. He did not immediately return a message left at his office by the Associated Press.

The prosecutor’s office had no immediate comment.

Medical experts testified that the baby died quickly after her temperature reached between 107 to 108 degrees Fahrenheit. They said she probably was in the microwave for more than two minutes.

“She died because she was overheated,” said Dr. Marcella Fierro, retired chief medical examiner for Virginia. “She was cooked.”

It was Arnold’s third trial in her daughter’s 2005 death. Her first trial ended in a mistrial when new witnesses surfaced just before closing arguments. Her second trial ended in a guilty verdict and a life sentence. But an appeals court overturned the conviction when it found prosecutorial misconduct and said the trial judge erred in not allowing a relevant witness to testify.

The sentencing phase was delayed earlier this week to allow time for a mental exam of Arnold. Two psychologists testified Thursday that Arnold was of average intelligence and showed no signs of serious mental illness.

Dr. Jeffrey Smalldon said Arnold suffered from a “low-grade chronic depressive condition” as well as alcohol and drug abuse. He said he found nothing “that would have justified the death of this child.”

In arguing for the death sentence, Assistant Montgomery County Prosecutor Dan Brandt told the jury there were no factors that mitigate the “purposeful murder of baby Paris in that microwave.”

Defense attorney Kevin Lennen said that death or life in prison would be a tough penalty, but death should go only to the worst offenders. He pointed to evidence that Arnold was drunk at the time of the baby’s death.

First Published May 20, 2011, 6:12 p.m.