An American woman convicted as a pregnant teenager of helping to kill her mother at an Indonesian luxury hotel was released from prison on Friday after six years behind bars.

In a case dubbed the 'suitcase murder', Heather Mack was handed a 10-year jail term in 2015 while her boyfriend Tommy Schaefer got 18 years for the murder of Chicago socialite Sheila von Wiese Mack on the holiday island of Bali.

Schaefer beat the 62-year-old victim to death with a fruit bowl during an argument at the five-star St. Regis resort.

The couple then stuffed the woman's body into a suitcase and tried to flee with it in a taxi, but quickly abandoned the blood-soaked luggage.

Mack, who was pregnant at the time of the crime, was found guilty on a lesser charge of assisting in the murder.

The 25-year-old was freed from Bali's Kerobokan prison on Friday, the head of its female section said, adding that Mack had been granted early release for good behavior.

"When she was released, she was a bit shocked and emotional. She hesitated and was scared, but we cheered her up," said prison official Lili, who like many Indonesians goes by one name.

Sentence reductions are common in the Indonesian justice system.

Wearing sunglasses, Mack was rushed out of the prison and into a waiting van surrounded by media.

She said "Thank you, Indonesia" in the local language as she was driven away by immigration officials to await deportation back to the United States.

'Changed a lot'

Bali's immigration office declined to comment on her case or say when Mack would be flown back home.

It was not immediately clear if her now six-year-old daughter, who was being raised in a Bali foster home, would also be deported at the same time.

Earlier, Mack's lawyer told AFP that she did not want her daughter to be deported and "hounded by the (US) media".

Since the pandemic, Mack -- now fluent in Indonesian and Balinese -- has had only video contact with her daughter, the prison official Lili said Friday.

"When she was inside she always followed our guidance programs and attended church sessions," Lili added.

"Heather has changed a lot."

The 2014 murder shook the usually sedate holiday island, with details of the grisly killing emerging during the closely followed trial.

The court heard how von Wiese Mack's badly beaten body was discovered in the taxi outside the ritzy hotel where she had been staying with her daughter and Schaefer.

The couple had fled to another part of Bali, where police arrested them.

Schaefer, who remains in prison, confessed to the killing during his trial but claimed he was defending himself during an argument with von Wiese Mack, who was unhappy that her daughter was pregnant.

Prosecutors alleged that Schaefer "blindly hit" von Wiese Mack with the fruit bowl in a fit of rage after she hurled a racial slur at Schaefer, who is Black.

During the attack, Mack hid in a bathroom but later helped Schaefer stuff the body into a suitcase, the trial heard.

The sentencing judge described the killing as "sadistic".

Locals and foreigners alike were horrified at the rare murder on Bali, a pocket of Hinduism in Muslim-majority Indonesia famed for its palm-fringed beaches.