The Supreme Court on Thursday upheld a life sentence for a woman who was convicted of killing her former husband, dismembering his body and dumping it into the sea. However, she was cleared of another murder charge for allegedly suffocating her 4-year-old stepson, due to lack of evidence.

Koh Yu-jeong, 37, was sentenced to life in prison in previous rulings by lower courts in February and July, upon conviction for the murder of her former husband, surnamed Kang, and for hiding his body.

On May 25 last year, she allegedly stabbed Kang to death after drugging him at lodgings on Jeju Island. She is suspected of mutilating his body and disposing of parts of it both at sea and at a waste disposal site in Gyeonggi Province. The body was never fully recovered.

Koh has admitted to the killing, but insisted it was accidental and that he had tried to sexually assault her.

“We found the defendant’s argument not reliable, which claimed that her former husband had attempted to rape her before the murder,” the court said.

The court said the murder was carefully planned, citing her purchase of the sleeping pill zolpidem and other tools ahead of the crime.

Bereaved members of Kang’s family said the punishment was too lenient.

“Given the defendant’s unreflective behaviors planning the killing, executing it in a brutal manner and blaming the victim for her action, life imprisonment is too light a sentence for her,” Kang’s brother said.

In a separate case, she was indicted on a murder charge for allegedly killing her 4-year-old stepson by suffocating him while he was asleep in their home in Cheongju, North Chungcheong Province, March 2, 2019.

Koh has denied killing the boy, who was the child of her new husband, surnamed Hong.

The Supreme Court said it could not rule out the possibility that the boy’s father, who was also asleep in the same bed, may have accidentally suffocated his son. Hong had taken sleeping pills that night, according to the court.

Hong has accused the judges of falling for Koh’s lies, asserting he has no sleeping habits that would have put his son’s life at risk.

By Park Han-na (hnpark@heraldcorp.com)