Ex-cellmate testifies mother admitted killing baby in microwave

"She said she put the baby into the microwave and started it and left the house," Williams said.

Williams said she asked Arnold how she got the child into the oven. "She said she fit right in," Williams said.

Sitting at the defense table, Arnold, 27, showed little emotion as her trial got underway in the August 2005 death of Paris Talley at their Dayton home.

Under cross-examination by defense attorney Jon Paul Rion, Williams acknowledged that she met with detectives after the alleged conversation and told them Arnold had said she didn't know how the baby died.

Williams, who has since been released from jail, said she lied to detectives in that initial interview because she had feelings for Arnold.

In his opening statement, Rion said, "The evidence is going to show that she did not purposely take the life of her own baby."

Rion said that other people had access to the baby, that Arnold was intoxicated to the point of blacking out when the child died, and that people questioned about the case changed their stories. Rion also raised questions about the reliability of the science when it comes to determining the effect of microwaves on humans.

Coroner's officials have said the baby suffered high-heat internal injuries and had no external burns. They have ruled out scalding water, open flame, or other possible causes of death that could have damaged the skin.

During the opening statement by Assistant Montgomery County Prosecutor Daniel Brandt, a photo of the burned baby was flashed on a screen for the 12-member jury to see. Arnold sat quietly, occasionally jotting notes on a yellow legal pad.

Brandt said Arnold killed the child after arguing with her boyfriend over whether they had been faithful to each other.