South Korea’s Supreme Court has finalized a 20-year prison sentence for a woman convicted of child abuse resulting in the death of a 17-year-old boy. The woman ran a study room in Busan’s Nam District, repeatedly urged the boy’s mother to punish him harshly and took part in the assaults; on the day he died, he was beaten for about seven hours while bound at home.

The appellate court changed the conviction from child abuse murder to child abuse resulting in death, finding insufficient proof of intent to kill or a joint-perpetrator relationship, and the Supreme Court upheld that ruling. The boy’s mother is serving a separate 25-year sentence for abusing and killing him.