South Korean police in Wonju say they’ve made headway into a drug use case involving four soldiers, two of the soldiers’ wives and a South Korean civilian man.

Police said all but one of the Camp Long-based soldiers has admitted to illegally using ketamine, an animal tranquilizer. One soldier has maintained his innocence, police said.

Urine samples for the six were sent Tuesday to a lab, and police expect results in the next week or two, a South Korean police officer said Wednesday on the customary condition of anonymity.

Police have said that drug-test results for the South Korean man, identified as Cho, 24, were positive. He remains in custody.

All other personnel involved fall under the U.S.-South Korea Status of Forces Agreement and are not in South Korean custody. The SOFA defines how U.S. military community members are treated within the South Korean legal system.

One of the wives is a South Korean citizen, police have said. Because she falls under the SOFA, police said they will treat her the same as the Americans in the case.

The police officer said the suspects claim to have bought the ketamine at a club in Seoul.

Eighth Army officials have confirmed they are cooperating with an ongoing investigation into illegal drug use in Wonju, but declined to name any of those involved.

Ketamine has become popular at dance clubs and rave parties in the United States. It also is reportedly used as a date-rape drug, according to the U.S. Drug Enforcement Administration.

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