Nancy Kissel's lawyers say evidence rules were breached
Hong Kong's top court has overturned the conviction of American woman Nancy Kissel for the murder of her investment banker husband.
The court ordered a retrial for Mrs Kissel, jailed for life for putting sedatives in husband Robert's milkshake and bludgeoning him with an ornament.
Her lawyers say prosecutors breached evidence rules during the trial.
The 2005 case heard tales of wealth, adultery, cocaine abuse, violent rows, greed and unhappiness.
"The court unanimously allows the appeal, quashes the conviction and orders a retrial," Court of Final Appeal chief justice Andrew Li said.
The 45-year-old mother of three, who lost her first appeal, has been serving a life sentence since she was convicted.
Her lawyer, Simon Clarke, told reporters Mrs Kissel was "very frail, emotionally and physically" and had been "psychologically injured" by the trial process.
Body in carpet
Mrs Kissel had admitted killing her husband, a banker at Merrill Lynch, in November 2003, but had denied murder, a charge that requires premeditation.
Prosecutors said she had given Robert, 40, a strawberry milkshake spiked with sedatives, before cracking his skull several times with a heavy statuette.
Mrs Kissel had tried to dispose of his body by rolling it up in a carpet and putting it into a storage room at the luxury Parkview apartments complex on Hong Kong island.
But the stench soon gave her away.
The court ruled the jury that convicted Mrs Kissel could have been misdirected.
"Mrs Kissel killed Mr Kissel. That much is not in dispute. But was the killing certainly murder or might it have been in self-defence?" the court judgement read.
The question was whether, given the evidence provided, a jury "would inevitably feel sure that Mrs Kissel was lying from start to finish and that she had planned and carried out a coldly calculated murder", said the court.
The BBC's correspondent in Hong Kong, Anne Marie Evans, says the case, involving expatriates who seemingly had everything, has enthralled Hong Kong.
Revelations at the original trial about the lifestyle of some members of the territory's wealthy elite gripped the public imagination.
Mrs Kissel lost an appeal in 2008 based on her claim that she acted in self-defence as her husband was threatening her with a baseball bat.
At the trial, prosecutors argued that she had planned the murder due to her uncontrolled passion for a new lover, a TV repairman in the US.
They alleged Mrs Kissel had stood to gain up to $18m (£11m) in life insurance payouts from her husband's death.