The Supreme Court has confirmed a 30-year prison term for a man who murdered his older sister and abandoned her body on a west coast island in 2020, officials said Thursday.

The 28-year-old man, whose identity was withheld, was convicted of stabbing his older sister, in her 30s, multiple times and killing her at an apartment building in Incheon, about 40 kilometers west of Seoul, on Dec. 19, 2020.

He put the victim's dead body in a piece of luggage and hid it inside storage on the rooftop of the apartment building for nine days before abandoning the corpse in a waterway running through a farm on the nearby Ganghwa Island, according to court records.

The man was found to have committed the crime while quarreling with the victim about his unpaid credit card payments, propensity for stealing and other behaviors.

He tried to cover up his crime by faking as if the victim was alive by showing police officers manipulated mobile messages he received from his sister. Police were investigating the victim's disappearance at the time following a missing person's report filed by her parents.

He also withdrew money from his dead sister's bank account and spent it.

The man was arrested a few days after the police found the victim's body in April of last year, four months after the crime.

"A 30-year prison sentence is not heavy considering the motive, method and result of the crime, as well as his actions after the crime," the top court said, upholding the lower courts' rulings. (Yonhap)