Woman who spent 43 years behind bars has murder conviction overturned

A woman who was a psychiatric patient when she incriminated herself in a 1980 Missouri murder has had her conviction overturned after spending 43 years behind bars.

Sandra Hemme. Pic: Missouri Department of Corrections/AP

Sandra Hemme's lawyers say a disgraced police officer was responsible for the killing of 31-year-old library worker Patricia Jeschke and this is the longest time a woman has been imprisoned for a wrongful conviction in US history.

Judge Ryan Horsman ruled on Friday the 63-year-old had established evidence of actual innocence, said her trial counsel was ineffective and prosecutors had failed to disclose evidence that would have helped her.

He said she must be freed within 30 days unless prosecutors retry her, but her lawyers, with the New York-based Innocence Project, are seeking her immediate release.

"We are grateful to the Court for acknowledging the grave injustice Ms Hemme has endured for more than four decades," they said in a statement, promising to keep up their efforts to dismiss the charges and reunite Hemme with her family.

The brutal killing of Ms Jeschke grabbed the headlines after her worried mother climbed through her apartment window in in St Joseph, Missouri, and found her daughter's naked body on the floor surrounded by blood on 13 November 1980.

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Her hands were tied behind her back with a telephone cord, and a pair of tights was wrapped around her throat, with a knife under her head.

Ms Hemme was shackled in leather wrist restraints and so heavily sedated she "could not hold her head up straight" or "articulate anything beyond monosyllabic responses" when she was first questioned over Ms Jeschke's death, according to her lawyers.

They alleged in a petition seeking her exoneration that authorities ignored her "wildly contradictory" statements and suppressed evidence implicating Michael Holman, then a 22-year-old police officer who tried to use the murdered woman's credit card on the day her body was found.

The judge found that "no evidence whatsoever outside of Ms Hemme's unreliable statements connects her to the crime".

"In contrast," he added, "this Court finds that the evidence directly ties Holman to this crime and murder scene."

Holman, who had been a suspect and was questioned at the time, was fired after investigations for burglary and insurance fraud, and died in 2015.