HONG KONG (Reuters) - A Hong Kong jury on Friday unanimously found an American woman guilty of murdering her Merrill Lynch banker husband in 2003, ending the lengthy retrial of a case that riveted the territory with tales of rough sex, marital violence and adultery.

Nancy Kissel, who has appeared in a wheelchair during nearly 10 weeks of proceedings at Hong Kong’s High Court, had already been sentenced to life in prison in 2005 for murdering senior Merrill Lynch investment banker Robert Kissel by giving him a milkshake spiked with sedatives and then clubbing him to death with a metal statuette.

Kissel, in her mid-40s, had been convicted of murder. But in the retrial, she had pleaded guilty to the lesser charge of manslaughter, with the defense arguing that she suffers from depression and had been provoked into the crime after years of sexual and physical abuse by her husband.

After the verdict from the jury of seven women and two men was read out, Kissel, looking pale and thin, rocked backwards and forwards slowly as members of her family broke down in tears and held one another.

Justice Andrew Macrae described the retrial as a “difficult and very serious one” while saying that his “hands were tied” in upholding Kissel’s life sentence in accordance with Hong Kong punishment for murder, despite mitigating arguments put forward by Kissel’s lawyers.

“I don’t wish to say anything to add to your anguish,” Macrae said simply to Kissel, who struggled to stay on her feet as prison wardens led her from the courtroom.

Speaking outside the court building to reporters, Kissel’s elderly mother, Jean McGlothlin, said with tears in her eyes that she was “shocked by the outcome,” while expressing concern for the frail physical condition of her daughter.

Kissel’s step-father, Michael McGlothlin, said he thought the unanimity of the decision by the jurors was bewildering. “Certainly there are grounds for appeal,” he said.

The so-called “milkshake murder” case engrossed Hong Kong with its tales of domestic violence, rough sex and adultery that fractured the high-flying expatriate lifestyle that many financial professionals in the former British colony enjoy.

Prosecutors said Kissel gave Robert a milkshake laced with a “cocktail of drugs” before cracking his skull several times with a statuette. They said Robert had planned to divorce Nancy and wanted custody of their children after discovering she had an affair with a TV repairman in the United States.

After the killing, she left the corpse in the master bedroom for several days before rolling it up in the living room carpet and having it carried into a storeroom at the couple’s luxury apartment complex perched in the lush hills of Hong Kong island.

The defense had sought to argue that Kissel was suffering significant emotional problems and psychological distress from years of bullying by her husband that led to the killing in an “abnormality of violence.”

Last February, following an appeal to Hong Kong’s highest court, Kissel won a stunning reprieve when the panel of judges quashed Kissel’s conviction and ordered a retrial, saying the case had been flawed and riven with conflicting evidence.

The retrial which began in January and lasted 10 weeks clearly took an emotional toll on Kissel, who often appeared listless and pale in court, at times breaking down and even once screaming that she could see her dead husband in the courtroom.

Many Kissel supporters were bitterly disappointed, including her father Ira Keeshin who hobbled away with a walking stick and refused comment. But many echoed the view of her lawyer Colin Cohen who said: “We regret the verdict ... but in my view, we have had a very fair trial.”