By Christine LaCrois

PHOENIX (KTVK/CNN) - An Arizona mother who was convicted of plotting her son's murder is closer to freedom.

A judge overturned her conviction Thursday, more than 20 years after her four-year-old son was found dead.

Her conviction hinged on the testimony of one key witness.

"Oh man, he was my pride and joy. I mean he was so much more brighter than me and stronger," said Mark Milke.

Christopher Milke was just 4-years-old in 1989 he was told he was going to go see Santa at the mall.

Instead, two men, friends of Debra Milke, drove him to the desert and shot him three times in the back of the head, allegedly on her orders.

The plot as outlined by prosecutors was all about collecting the boy's life insurance. And Debra Milke was convicted of murder. That conviction was overturned.

"All I can tell you is I was so elated I could hardly think," said her attorney, Michael Kimerer.

Aattorneys Mike Kimmerer and Laurie Voepel have been fighting for Debra's release. She has always maintained that she had nothing to do with Christopher's death.

Her conviction was based largely on the testimony of a former detective, Armando Saldate who said she confessed to him. Here's what he later told 3TV:

"She then manipulated two other gentlemen to get rid of the child and they got rid of the child and made up a story that he got lost in the mall," he said.

But detective Saldate had a history of misconduct that the prosecution failed to disclose.

"The court's opinion makes it very clear that they are very unhappy with the detective's conduct in this case," said Voepel.

According to the court documents, Saldate never read Debra her rights, and the state of Arizona never disclosed that Saldate had a long history of lying under oath.

While Debra's ex husband, Christopher's father, believes she is guilty of murder, he also believes that Saldate botched the investigation. He never recorded the alleged confession.

"He was order to tape record that. He flew off in his little helicopter, didn't even take the tape recorder with him. Didn't even plan on tape recording it. He was going to tell it the way he was going to tell it," said Mark Milke.

A story now being questioned, and a woman who spent the last 22 years on death row, now waiting and wondering if she will walk free.

"She has been sitting there every day thinking, 'I could get the word any minute they're going to pull the trigger and I'm going to be facing the death sentence,'" said Kimmermer.

The judge ordered the state to turn over Saldate's personnel records to Milke's lawyers and have "a police official" state under oath that everything has been disclosed.

Once this is done, a district court must order Milke's release unless prosecutors tell the court within 30 days that they plan to retry her.

The Arizona attorney general says he plans to appeal the judge's decision to overturn the conviction.