A jury found Debra Milke guilty of murder in 1990 in connection with the brutal death of her 4-year-old son Christopher.
But earlier this year, a U.S. Appeals court threw out the conviction, based on a tainted confession obtained by a Phoenix police officer with a history of misconduct.
As a result, Milke is getting a new trial, which is set to begin later this month.
Former Maricopa County prosecutor John Rhude told CBS 5 News that the testimony of Officer Armando Saldate will hold the key to whether Milke is found guilty again.
"If that officer is not credible, if the words that come out of his mouth cannot be verified, if there's serious questions to his motives and the authenticity and honesty of that officer - there's a real big problem for Mr. Montgomery and the county attorney's office."
Other potential problems for Maricopa County Attorney Bill Montgomery include:
Evidence that's old, or doesn't exist anymore.
Witnesses that may no longer be available.
Testimony based on events - 20-plus years ago.
Montgomery has repeatedly stated that he's moving forward with the case, because he's convinced Milke belongs behind bars for the brutal murder of her son.
Private investigator Paul Heubl interviewed Milke twice from jail and conducted extensive research on the case.
Heubl said that he believes Milke will be found not guilty.
"I have searched far and wide for any piece of evidence that I could," said Heubl. "I am a trained investigator. I'm a former police officer. I've looked and looked and never could find one shred of evidence linking her to this crime."
Milke's former roommate James Styers remains in prison for the murder of Milke's son. Styers has never come forward to say Milke was involved.
A court hearing will be held Sept. 23 to determine whether the confession obtained by Saldate will be allowed in the new trial, which is set to start Sept. 30.
Copyright 2013 CBS 5 (KPHO Broadcasting Corporation). All rights reserved.
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