A federal appeals court overturned the convictions of an Arizona woman who was sentenced to die after being found guilty of orchestrating a gruesome plot to murder her 4-year-old son for insurance money in 1989.

The court ruled Debra Jean Milke's case was tainted by a detective with a history of lying under oath.

The case made national headlines due to the brazen and gruesome nature of the crime. Prosecutors said Debra Jean Milke dressed up her son Christopher in his favorite outfit and told him he was going to see Santa Claus at a mall during the holidays.

Instead, he was taken into the desert by her boyfriend and another man and shot three times in the back of the head as part of what prosecutors said was a plot by Milke and the two other defendants to collect a $50,000 life insurance policy.

Milke has always maintained her innocence, Fox 10 reports.

"It just amazes me that people can say I was so abusive while it was never reported, no one tried to take him away from me," Milke told Fox 10 in a jail house interview in 1990. "I did the best that I could with what I had."

The three-judge panel of the 9th U.S. Circuit Court of Appeals says the prosecution failed to disclose information about a history of misconduct by then-Phoenix police detective and trial witness Armando Saldate.

That record included multiple court rulings in other cases that Saldate  either lied under oath or violated suspects' Miranda rights during interrogations.

Saldate testified that Milke confessed to him that she had plotted her son's murder. However, there was no other witness or a recording of the purported confession.

Prosecutors are required to provide a defendant's lawyers with material that might support a not guilty verdict, including material that could undermine the credibility of a prosecution witness.

"No civilized system of justice should have to depend on such flimsy evidence, quite possibly tainted by dishonesty or overzealousness, to decide whether to take someone's life or liberty," Chief Justice Alex Kozinski wrote in the decision.

The trial amounted to "a swearing contest" in which the judge and jury ultimately believed the detective over Milke, but they didn't know of his record of dishonesty and misconduct, Kozinski wrote.

Milke would have been the first woman executed in Arizona since the 1930s had her appeals run out. The Arizona Supreme Court had gone so far to issue a death warrant for Milke in 1997, but the execution was delayed because she had yet to exhaust federal appeals.

The ruling reversed a U.S. District Court judge's ruling and ordered the lower court to require Arizona authorities to turn over all relevant personnel records for the detective.

Once the material is produced and defense lawyers have time to review it, prosecutors will have 30 days to decide whether to retry her. If they don't, she will be released from prison.

Maricopa County prosecutors had yet to read the ruling and had no immediate comment on the decision, spokesman Jerry Cobb said, but Arizona Attorney General's Office said it was reviewing the case and will likely file an appeal.

The young boy's father slammed the ruling Thursday, telling Fox 10 he is unhappy with the decision.

"My message?  I think they are a bunch of pompous (expletive)...they are ultra liberal.  Let them pony up the money for her to stay on death row," AZ Milke said.

Milke, 48, is one of three women on death row in Arizona. All three are imprisoned at the state prison for women in Goodyear.

The two men convicted in the Milke's case, Roger Scott and former Milke roommate James Styers, are both on death row at a prison in Florence.

Scott confessed during a police interrogation and led detectives to the boy's body, but neither Scott or Styers would testify against Milke.

Click for more from Fox 10. 

The Associated Press contributed to this report.