PHOENIX -- Prosecutors in a case against an Arizona mother whose 1990 conviction in the killing of her young son was overturned have appealed a ruling that allows a key witness to assert his right against self-incrimination and refuse to testify against her at a retrial.
Authorities say Debra Milke had two men shoot her 4-year-old son in the desert outside Phoenix in 1989. But after more than two decades on death row, an appeals court last year overturned her first-degree murder conviction.
Milke was released on bond and awaits a 2015 retrial.
The case against Milke rested largely on her purported confession, which now-retired Phoenix police Detective Armando Saldate did not record. That left jurors with his word alone that she told him about her involvement. Milke has maintained her innocence and denied she ever confessed.
After hearing arguments, Judge Rosa Mroz granted Saldate's request to assert his Fifth Amendment right against self-incrimination and refuse to testify at Milke's retrial.
In its ruling overturning her conviction, the 9th U.S. Circuit Court of Appeals cited, in part, the prosecution's failure to reveal evidence that could have called Saldate's credibility into question.
The court cited numerous instances in which he committed misconduct in previous cases, including lying under oath and violating suspects' rights- details that were not provided to Milke's defense lawyers during her trial.
Saldate now claims he fears potential federal civil rights charges based on the appeals court accusations of misconduct.
Mroz's ruling allowing him to assert his Fifth Amendment right effectively gutted the state's case. Without Saldate's testimony, the judge said, the purported confession would most likely not be allowed at Milke's retrial.
``By allowing the witness to invoke `blanket' privilege, respondent judge's order prevents the witness from disclosing relevant information that is essential to the truth-seeking function of a trial,'' prosecutors wrote in a filing this week with the state Court of Appeals.
Oral arguments on the motion have been set for March 5.
Defense attorneys are seeking dismissal of the entire case against Milke, noting in a previous motion that ``the only direct evidence linking defendant to the crimes is the defendant's alleged confession to Saldate.''
Saldate and his attorney have not returned repeated phone calls from The Associated Press.
Prosecutors argue that if Saldate doesn't testify again, it ``will cause irrevocable harm to the state's ability to present its case and will deny the victims' constitutional rights to justice and due process.''
They also contend that Saldate has not met the burden for establishing a reasonable fear of prosecution if he testifies, noting that county and federal prosecutors have said they don't plan any charges against him.
Saldate's attorney argued that prosecutors offered no guarantees that his client wouldn't face charges in the future.
The two men convicted in the child's death did not testify against Milke and remain on death row.