FARGO, N.D. (AP) — A pair of Chinese nationals has been indicted on charges that they manufactured tons of fentanyl and other powerful narcotics that were peddled in the United States and flowed, in part, through North Dakota.

Authorities said the men controlled one of the most prolific international drug-trafficking organizations but with no extradition treaty with China, the changes are slim they will ever be brought to the U.S. to face the charges.

One of the two, 38-year-old Jian Zhang, was indicted in the District of North Dakota, along with eight others accused in the conspiracy.

North Dakota U.S. Attorney Christopher Myers says the whole investigation began in January 2015 with the overdose death of 18-year-old Bailey Henke in Grand Forks. Officials say American customers could purchase pure fentanyl and other dangerous drugs online, directly from Chinese factories. Inexperienced users don't know the drug is pure and overdose.