The top court has upheld a 23-year prison sentence for the main culprit behind the drugging of unconsenting students in Seoul’s Gangnam area in order to extort money from their parents.

Legal sources said Tuesday that the Supreme Court upheld a lower court’s decision to convict the person, surnamed Lee, under the Narcotics Control Act.

Lee was found guilty of ordering South Korean and foreign accomplices to manufacture and distribute drug-laced drinks.

Lee instructed his accomplices to distribute the drinks to minors in Daechi-dong, an area of Gangnam known for its private education institutions.

The drinks were distributed to 13 minors, nine of whom consumed the drink, and six of the victims reported experiencing hallucinations.

The perpetrators contacted the parents of the students who consumed the drug-laced beverage and attempted to extort money from them by threatening to report the victims to the police for drug use.