The Transportation Security Administration has finally solved a massive interagency drug scandal that began in 1998.

At least a dozen current and former TSA employees trafficked approximately 20 tons of cocaine through Luis Muñoz Marín International Airport in Purto Rico for nearly 20 years, according to a report from the Department of Justice.

The agents involved created an elaborate plan that smuggled suitcases of 8 to 15 kilograms of cocaine through TSA checkpoints, coordinating their efforts with other agents at the X-ray machines.

So far, six current and six former employees have been arrested and charged with crimes related to drug trafficking.

“These individuals were involved in a conspiracy to traffic massive quantities of illegal narcotics to the continental United States,” Rosa Emilia Rodríguez-Vélez, U.S. Attorney for the District of Puerto Rico, said in a statement. “These arrests demonstrate the success of the AirTAT initiative, which has successfully allocated a dedicated group of state and federal law enforcement officers, whose mission is to ensure that our airports are not used in the drug traffickers’ illicit businesses.”

The names of six of the agents are José Cruz-López, Luis Vázquez-Acevedo, Keila Carrasquillo, Carlos Rafael Adorno-Hiraldo, Antonio Vargas-Saavedra, and Daniel Cruz-Echevarría.