Police arrested a man Thursday on suspicion of growing marijuana in a greenhouse on the rooftop of an office building in Jung-gu, central Seoul.
The man surnamed Lee, 45, allegedly grew a bunch of cannabis plants and sold 31 grams of marijuana.
Lee brought 20 marijuana seeds from Canada via international couriers in December and raised them in the greenhouse on the rooftop. The greenhouse was equipped with ventilation, lighting and a heating system which cost him 1.6 million won in monthly electricity charges.
Police said the cannabis could harvest a total of 270 grams of marijuana worth an estimated 270 million won.
Lee previously served eight years in prison from 2001 for drug trafficking in the U.S. and was deported in December 2008.
He was quoted as saying that he decided to grow the illegal plants as it became hard to smuggle in the drugs from abroad.
An 18-year-old man surnamed Kim was also arrested for buying 31 grams of marijuana from Lee and reselling some of it to other consumers.
Police said the two suspects met through a secondhand on-line market through which overseas students deal drugs. Kim is suspected of selling seven grams of marijuana for 700,000 won to a 25-year-old man.