South Korea's top court upheld a lower court ruling that sentenced defendants in a high-profile drug scam -- in which drug-laced drinks were deceptively distributed to students, followed by the blackmail of their parents -- to prison terms of up to 18 years, the court announced on Friday.

The Supreme Court confirmed the lower court’s verdict, sentencing individuals identified by the surnames Gil, Kim, Park and Lee to prison terms of 18, 10, 10 and seven years, respectively. They were found guilty of various charges that included violations of the Narcotics Control Act and fraud.

Article 58-7 of the Enforcement Decree of the Narcotics Control Act stipulates that anyone who doses or delivers narcotics to minors for profit shall be punished by a minimum of five years in prison and a maximum of the death penalty.

The defendants distributed drinks containing methamphetamine and milk, disguised as a "memory-enhancing beverage tasting event," to middle and high school students going to private cram schools in Daechi-dong, southern Seoul, on April 3, 2023.

The perpetrators reportedly claimed that the drinks would help students concentrate. Thirteen students were deceived into taking the drinks. The perpetrators subsequently blackmailed the parents of these students, threatening to report their children for drug use unless they were paid, committing voice phishing.

These criminal activities were orchestrated by another individual with the surname Lee, who was separately sentenced to 23 years by the Seoul Central District Court in July for his role as the leader.

The mastermind, who was apprehended in China and extradited back to South Korea, initially claimed he was merely participating as a favor. However, the court found he actively recruited others, including Gil, to execute the plan.