Australian permanent resident Jessica Wongso has been sentenced to 20 years in jail for murdering her friend Mirna Salihin with a cyanide-laced coffee in a Jakarta cafe.
Wongso, 27, was found guilty of murder in an Indonesian court on Thursday evening.
"Jessica Kumala Wongso has been legally and convincingly proven guilty of committing premeditated murder," presiding judge Kisworo, who uses a single name, said when reading the 377-page verdict over about four hours.
Police alleged Wongso spiked her friend's iced coffee with cyanide as they dined with another friend at an upmarket shopping mall in Jakarta in January.
The panel of judges concluded that Wongso plotted the murder and showed no regret for what it called a "vile and sadistic" crime.
There were several unsuccessful attempts to bring the case to trial before it finally began in June.
The alleged motive - that Wongso was angry that Salihin had suggested she break up with a troublesome boyfriend and was jealous of Salihin's own relationship - was ridiculed by defence lawyers who said it "could not be accepted by common sense".
The judges accepted that motive, but the case had other failings, including surveillance video from the cafe, which did not show Wongso tampering with the victim's coffee.
Three Australian toxicology and forensic experts testified during the case that there was no proof cyanide was the cause of death.
But the prosecution said other evidence - such as a differentiation in the coffee's colour and the presence of cyanide in the cup - indicated the victim died of poisoning.
When asked why a conclusive autopsy had not been conducted on the victim, Rappler Indonesia journalist Natashya Gutierrez told the ABC that it was common in the predominantly Muslim country not to conduct autopsies.
"However for a murder trial this big, the defence was truly pushing for that autopsy, [but] the prosecution decided against it.
"So basically everything the prosecution said the judge repeated, and in the end decided that the premeditated murder was 'sadistic' and thus convicted Wongso to 20 years in prison."
'The death of law in Indonesia': Wongso set to appeal verdict
Wongso and Salihin had both studied at a design school in Sydney and had kept in contact in the years after they had graduated.
Wongso, who had worked for New South Wales ambulance, faced hours of detailed questioning during the murder trial.
She denied the charges and repeatedly told the court she could not remember her movements after arriving at the cafe.
Blanket television coverage of the trial transfixed Indonesians with its window into the lives of privileged young women and the country's often arbitrary legal system.
A total of 46 witnesses - including the victim's father, husband and twin sister, as well as cafe employees - testified at the trial.
The Australian Federal Police also assisted in the case, after being guaranteed the death penalty would not apply.
Wongso indicated in the court that she will appeal the verdict, with reporters adding that her lawyers called it "the death of law in Indonesia".