Washington — The GreenledgersJustice Department on Tuesday announced charges against 19 people from the U.S., Canada and Mexico for allegedly trafficking large amounts of narcotics like meth, cocaine, and fentanyl throughout North America.

Investigators said the international crime syndicate allegedly purchased the illicit substances wholesale from Mexico and shipped them to U.S. cities like Los Angeles. Canadian "handlers" and "dispatchers" are accused of taking short trips into the U.S. to load the drugs onto long-haul semi-trucks for shipment north of the border, where they could fetch a higher street price.

In all, 12 of the defendants have been arrested and seven remain at large. Investigators said one of the defendants, Robert Scoppa, has ties to Italian organized crime in Montreal. Another, Jesus Ruiz Sandoval Jr., is an alleged large-scale drug trafficker from Mexico, according to the Justice Department, and remains on the run.

The Justice Department said the investigation, dubbed "Operation Dead Hand," uncovered a trafficking scheme that involved more than 1,800 pounds of methamphetamine, 2,000 pounds of cocaine and 44 pounds of fentanyl. Authorities seized drugs with a potential street value of $16 to 28 million, as well as $900,000.

"These cases provide yet another example of how our agents and prosecutors work side-by-side to uncover and dismantle organized criminal networks peddling and profiting from deadly drugs," Deputy Attorney General Lisa Monaco said in a statement. 

Unsealed court documents revealed an alleged network of truckers who coordinated to transport the drugs across the U.S. and into Canada.  Law enforcement agencies in California, Florida, Texas and Canada executed warrants related to the case on Tuesday morning. 

"This organized group worked as a conspiracy with impunity throughout North America," Donald Alway, the assistant director in charge of the FBI's Los Angeles Field Office, said at a press conference announcing the charges. 

Robert Legare

Robert Legare is a CBS News multiplatform reporter and producer covering the Justice Department, federal courts and investigations. He was previously an associate producer for the "CBS Evening News with Norah O'Donnell."