An Arizona woman who spent two decades on death row in the killing of her 4-year-old son will speak out for the first time since she had her case dismissed.

Debra Milke was scheduled to hold a news conference Tuesday, a day after a judge formally dismissed a controversial case that relied almost entirely on the work of a detective with a long history of misconduct.

Milke, 51, was convicted of murder in 1990 in the death of her son, Christopher. Authorities say Milke dressed him in his favorite outfit and told him he was going to see Santa Claus at a mall in December 1989. He was then taken to the desert near Phoenix by two men, one of whom was Milke's roommate, and shot in the back of the head.

Authorities say Milke's motive was that she didn't want the child anymore and didn't want him to live with his father. Milke has maintained her innocence and denied that she confessed to the killing. James Styers and Roger Scott, the two men who led Christopher to his death, have been on death row and have refused to testify against Milke.

While Milke sat on death row, the Arizona Supreme Court had gone so far as to issue a death warrant for her in 1997. The execution was delayed because she had yet to exhaust federal appeals.

An appeals court overturned Milke's conviction in 2013, ruling that prosecutors failed to disclose a detective's history of misconduct. Her conviction was based entirely on a confession Milke gave to the now-discredited detective, Armando Saldate.

Multiple rulings in other cases said the now-retired officer either lied under oath or violated suspects' rights during interrogations, according to the federal appeals court.

One of Milke's attorneys, Michael Kimerer, said Monday that he was still in disbelief that "a long, long journey with so many ups and downs" ended with his client's freedom.

"She was innocent. It was all based upon a police officer that just totally lied," Kimerer said outside court. "To see her free today and totally free and exonerated, it's an unbelievable feeling — just unbelievable."

Saldate's history of conduct included a five-day suspension after he stopped a female motorist in 1973 and "took liberties" with her before agreeing to meet her later for sex. According to court documents, he questioned a suspect in 1982 who was strapped to a hospital bed and was so incoherent he didn't even know his own name.

Saldate had said he would not testify at any retrial, citing fears of potential federal charges based on the 9th Circuit's accusations of misconduct. Both county and federal authorities said they did not intend to seek charges against the detective based on the accusations, and a state appeals court later ruled that Saldate would be compelled to testify even against his will.

Milke sued the city of Phoenix, Maricopa County and numerous individuals earlier this month, alleging authorities violated her civil rights. She also contends she was denied a fair trial and was a victim of malicious prosecution.

Milke, whose mother was a German who married a U.S. Air Force military policeman in Berlin in the 1960s, has drawn strong support from citizens of that nation and Switzerland, neither of which has the death penalty.

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Follow Terry Tang on Twitter at https://twitter.com/ttangAP .