A South Korean court has given a life sentence to a true crime fan who told police she murdered a stranger "out of curiosity".
Jung Yoo-jung, 23, had been obsessed with crime shows and novels and scored highly on psychopath tests, police said.
Fixated with the idea of "trying out a murder", she used an app to meet an English-language teacher, stabbing her to death at her home in May.
The brutal killing shocked South Korea.
Prosecutors had asked for the death penalty - a request typically reserved for the gravest of offences.
They told the court that Jung, an unemployed loner who lived with her grandfather, had looked for victims for months, using an online tutoring app to find a target.
She contacted more than 50 people and favoured women, asking them if they conducted their lessons at home.
In May, posing as the mother of a high school student who needed English lessons, she contacted the 26-year-old victim, who lived in the south-eastern city of Busan. Her identity has not been disclosed by police.
Jung then showed up at the tutor's house dressed in a school uniform she had bought online, prosecutors said.
After the teacher let her in, she attacked the woman, stabbing her more than 100 times - continuing the frenzied attack even after the victim had died.
She then dismembered the woman's body and took a taxi ride to dump some of the remains in remote parkland near a river, north of Busan.
She was arrested after the taxi driver tipped off police about a customer who had dumped a blood-soaked suitcase in the woods.
Police said Jung's online browsing history showed she had researched for months on how to kill, and how to get rid of a body.
But she was also careless, police said, and took no effort to avoid CCTV cameras, which captured her entering and leaving the tutor's home several times.
On Friday, a sentencing judge in the Busan District Court said the killing had "spread fear in society that one can become a victim for no reason" and "incited a general distrust" among the community.
Jung, who confessed to the crime in June, pleaded for a more lenient sentence, saying she had suffered hallucinations and other mental disorders at the time.
But the court rejected her argument as the crime had been "carefully planned and carried out, and it is difficult to accept her claim of mental and physical disorder".
They noted that her statements to police had frequently changed. Initially Jung said she had only moved the body after someone else killed the woman, then later claimed that the killing had occurred as a result of an argument.
In the end, she confessed that her interest in committing a murder had been piqued by crime shows and TV programmes. While South Korea retains the death penalty, it has not carried out an execution since 1997.
