Mother On Death Row Has Conviction Overturned

A mother on death row for 22 years for killing her four-year-old son in 1989 has had her conviction overturned.

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

Prosecutors had said Milke dressed up her son Christopher in his favourite outfit and told him he was going to see Santa Claus at a shopping centre 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.

The 49-year-old was convicted in October 1990. 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.

A three-judge panel said the prosecution failed to disclose information about a history of misconduct by detective Armando Saldate Jr, who said that Milke confessed to plotting her son's murder.

There was no other witness or recording of the purported confession by Milke, who has proclaimed her innocence.

"No civilised 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, Mr Kozinski wrote.

The ruling reversed a US 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 defence 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.

In 2009, Milke's defence lawyer Michael Kimerer said his client maintains her innocence and was a loving mother who still grieves her son's death.

"Our main concern is the fact that I have a client that never confessed and a police detective who said she gave a confession. There was no tape recorder, no witnesses, nothing. Just his word," Mr Kimerer said then.

Milke would have been the first woman executed in Arizona since the 1930s had her appeals run out.