The suspected drug dealers brought in 3.4 kilograms of marijuana from the US into Korea and sold 1.5 kilograms of it between March and September 2018 in Seoul, Incheon and the surrounding areas.
A couple -- surnamed Shim and Kwon -- used those holding US-Korean dual citizenships as well as Koreans who were expelled from the US after criminal convictions to carry the marijuana.
The police are trying to locate Kwon -- who fled Korea amid the investigation -- with the help of Interpol.
Many of the deportees and dual citizens involved in the drug smuggling worked as English language teachers here, according to police.
Police confiscated 2 kilograms of marijuana and some 77 million won ($65,340) they made through selling the drug.
They also apprehended 33 people who used marijuana, the police said.
By Ock Hyun-ju (email@example.com)