Matt York, Associated Press
Debra Milke speaks as Attorney Lori Voepel listens, Tuesday, March 24, 2015, in Phoenix. Milke spoke out for the first time after spending two decades on death row in the killing of her son. Her case was dismissed earlier this week.

PHOENIX — A woman who spent 22 years on death row in her son's killing tearfully described Tuesday how she suffered twin tragedies in losing her young child and being the victim of a "blatant miscarriage of justice."

Debra Milke spoke out at a news conference a day after her case was dismissed in the 1989 killing of her 4-year-old son, who thought he was going to see Santa Claus when he was taken to the desert and shot in the back of the head. Her conviction was overturned by an appeals court that ruled her murder conviction was tainted because of the work of a discredited detective.

Milke sobbed repeatedly as she read a statement about her ordeal, fondly recalling her son's love of bubble gum and riding his big wheel.

"Losing a child to murder is a devastating tragedy with an indescribable pain no parent should ever have to feel. It is the purest form of anguish imaginable that sears the soul, and the hurt never goes away, ever," she said. "The only thing worse is to be falsely accused of participating in your own child's death."

Milke was convicted of murder and sentenced to death based almost entirely on an unrecorded confession authorities say she made to Detective Armando Saldate. Her lawyers called him a "dirty cop" with a long history of misconduct.

"She's an innocent woman who never should have been convicted. She was the victim of a dirty cop," defense lawyer Michael Kimerer said.

Prosecutors insist that Milke had her son killed, but they lost their final appeal last week to have her retried in her son's death. Authorities say Milke's motive was that she didn't want the child anymore and didn't want him to live with his father. James Styers and Roger Scott, the two men who led Christopher to his death, 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.

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.

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.