Four UPS employees were arrested in the bust of a “sophisticated” drug- and cash-smuggling scheme that saw traffickers using the delivery service to ship counterfeit vape pens and other illicit goods from Mexico into the US for more than a decade, according to new reports.

The accused ringleader was a 20-year veteran of the shipping service at the company’s Tucson distribution center, who authorities allege used his position to hide the origin and destination of each illicit package, the Washington Post reported.

A total of 11 people have been collared in the bust, which capped a two-year investigation into the shipment of large amounts of narcotics to destinations throughout the eastern United States and bulk cash sent back to the Tucson, Arizona, area. The case is being handled by the Arizona Attorney General’s office.

UPS employees — both drivers and supervisors — used “sophisticated methods and techniques” to avoid detection by company officials and law enforcement to “identify and intercept parcels containing contraband,” ICE spokeswoman Yasmeen Pitts-O’Keefe told the Tucson Sentinel.

Dispatch supervisor Mario Barcelo, 49 — the accused ringleader — allegedly used his clout to ensure drug-packed boxes made their way onto certain trucks, and which slyly bypassed security measures in order to be delivered on time to the intended destination, according to the Washington Post.

The other UPS employees were identified as supervisor Gary Love, 40; and drivers Michael Castro, 34; and Thomas Mendoza, 47.

Some of the suspects arrested had been shipping illegal items through UPS for more than a decade and worked with multiple cartels, Tucson Police Capt. John Leavitt told the newspaper.

The ring allegedly shipped several thousand pounds of drugs weekly at its peak, Tucson Police Sgt. William Kaderly told the Washington Post.

“He’s been able to provide this service to drug traffickers without being detected both internally and externally by law enforcement for years,” Kaderly said of Barcelo. “They’ve been doing it for so long that they were truly comfortable that they were never going to get caught.”

“Their sales pitch was that because of who Barcelo was at UPS, he could make sure your package will make it out without anyone finding it,” he added. “He had face time with traffickers.”

Officers seized nearly 50,000 counterfeit vape pens, cash and more than a dozen vehicles in the probe, including Corvette and a Range Rover, Pitts-O’Keefe said.

“The vape pens that were confiscated are exactly the kind that the CDC warned about,” Leavitt told the Sentinel. “They are the pens that are likely implicated in the death and illness related to THC cartridges across the country.”

UPS reps said in a statement that the company was cooperating with law enforcement officials but couldn’t divulge additional information, citing an ongoing investigation.