(PHOENIX) -- An Arizona mother who was sentenced to death in the killing of her 4-year-old son had her conviction thrown out Thursday after she spent 22 years on death row.
A U.S. Circuit Court of Appeals ruled that Debra Jean Milke's murder conviction would not stand after they determined that a detective who testified against her in her trial had an undisclosed history of misconduct.
Milke was found guilty of murder for arranging the 1989 killing of her son Christopher.
According to prosecutors, two men told Christopher that he was going to see Santa Claus in December 1989, and then took him out into the Arizona desert and shot him. Authorities alleged Milke was behind the plot, and that her motive was insurance money, according to ABC News affiliate KNXV.
Prosecutors said Milke confessed to the crime but that Detective Armando Saldate, who obtained the confession, failed to tape-record it, according to KNXV. Milke denied that she ever confessed, but was found guilty and sentenced to death.
Saldate's history, according to the court ruling, includes eight cases in which judges tossed out confessions, indictments, and convictions because Saldate lied under oath or violated suspects' rights during interrogations. He was also suspended for "taking liberties" with a female driver he pulled over and lying about it, the court said.
On Thursday, the Ninth Circuit Court of Appeals found that because the prosecution did not disclose Saldate's history of misconduct, the conviction and sentence could not stand, according to the opinion released Thursday.
"Milke's conviction was based largely on the testimony of Police Detective Saldate, who allegedly obtained her confession," the court wrote in its decision. "The panel held that the state remained unconstitutionally silent instead of disclosing information about Det. Saldate's history of misconduct and accompanying court orders and disciplinary action."
The ruling mandated that Arizona authorities must turn over all of the information that was not disclosed during the trial to Milke's defense team. Once they do, the prosecution must decide whether to retry Milke.
Otherwise, she will be released from prison.
Milke's attorney did not immediately respond to ABC News' request for comment.
Milke is one of three women on death row in Arizona, and her reprieve comes as another high-profile death penalty case is being heard in the state. Jodi Arias is being tried in Maricopa County for the murder of her ex-boyfriend, Travis Alexander, and could face the death penalty if convicted.
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