In opening statements Monday, the defense attorney for China Arnold said a young relative of the victim killed her, not his client.
Jon Paul Rion said a new witness came forward while watching televised reports on the February trial. He said the witness, who was only five years old at the time of Talley's death, remembered being there when the girl was killed.
Rion said the boy, now eight, will testify that another child put Talley in the microwave. Rion said the defense believes a young cousin of the victim is responsible for the crime. Rion said the witness was able to accurately describe the child's burns.
During his opening statements, Rion told the jury that they would hear from several other boys who have admitted to hearing the cousin brag about Talley's death.
"(The cousin said) 'I'll tell you how the baby died if you swear not to tell anyone,'" said Rion. "(The cousin) then tells them that he put the baby in the microwave."
Rion said the boy told his friends that story before officers identified a microwave as the murder weapon. He said the boy bragged again once the new information became public.
"The story had just broken about how a microwave may have been used and (the cousin) says 'See, I told you I wasn't lying,'" Rion told the jury.
Rion said the new witnesses initially did not come forward because they were afraid of becoming suspects.
Prosecutors, however, told the jury that they have evidence to prove Arnold is responsible for the crime. They said she admitted her guilt to a cellmate.
Arnold has pleaded not guilty to a charge of aggravated murder. She could face the death penalty if she is convicted.
The trial is expected to take two to three weeks.