The Supreme Court has upheld guilty verdicts for twin sisters convicted of cheating on exams at Sookmyung Girls' High School using answers leaked by their father, who was a teacher at the school.

The Supreme Court on Tuesday upheld the previous decision by an appellate court which sentenced the sisters to one year in prison, suspended for three years.

The sisters were indicted for obstructing the school's evaluation duties by using exam answers stolen by their father, who at the time was the head of the school's academic affairs, during their first two years as students there in 2017 and 2018.

The twins consistently denied the charges from the first trial, claiming that their high exam scores were due to their diligence, not cheating.

The first trial sentenced them to 18 months in prison, suspended for three years, but the appeals trial reduced their sentence to one year in prison, suspended for three years.