Italian authorities seized a massive 4.3 tons of cocaine that had been shipped by the Clan del Golfo, a drug cartel based in Colombia.

According to Daily Mail, investigators said Tuesday it was the third-largest drug bust in Europe's history. Colombian authorities reportedly confiscated the cocaine shipment, with a street value of $255.86 million, before it left for Europe.

They said the Clan del Golfo did not know that authorities had already discovered their operation and seized the cocaine. A shipment was still flown to Italy, and when the Italian traffickers received what they thought was the drugs, they were immediately placed under arrest.

In a press conference on Tuesday, Colonel Leonardo Erre of the Trieste Guardia di Finanza police said: "The purchasing organizations were different and did not know that the cocaine had already been seized."

Erre added that the producer in Colombia had "already been paid and did not know about the seizure." Apart from the cocaine shipment, cops also seized $1.97 million in cash.

Italian investigators have reportedly issued arrest warrants for 38 people in Italy, Colombia, Croatia, Slovenia, Bulgaria, and the Netherlands. 

"So thanks to front companies and undercover agents, we were able to run the operation, delivery after delivery for over a year until the end of May," Erre said.

The investigation, which also involved the Colombian judiciary and U.S. Homeland Security Investigations, reportedly lasted more than a year.

READ NEXT: Baby Formula Shortage: Over 110K Pounds of Infant Milk to Arrive in Texas This Week

Clan Del Golfo Leader 'Otoniel' Arrested in Colombia

An operation in a rural area of Colombia's Uraba region, located in Antioquia province, in October last year resulted in the arrest of Clan Del Golfo leader Dairo Antonio Usuga, known by his alias "Otoniel."

It involved more than 500 members of special forces and 22 helicopters. The operation, named Osiris, which resulted in the death of one police officer, brought to an end years-long efforts to find and capture Otoniel.

Colombian President Ivan Duque said it was the "biggest blow to drug trafficking" in Colombia since the fall of Pablo Escobar. Otoniel stayed on the run for more than a decade.

The Clan Del Golfo leader reportedly managed to elude capture by corrupting state officials and aligning himself with combatants on the left and right. He also slept in a different rural location every night.

Otoniel has been accused of sending dozens of shipments of cocaine to the U.S., killing police officers, recruiting minors, and sexually abusing children, among other crimes. 

The Clan Del Golfo leader was extradited to the United States on May 5 and is being held in a New York City prison.

Colombia's Clan de Golfo Leader Dairo Antonio Usuga Likened to Drug Lord Pablo Escobar

Dairo Antonio Usuga has been on the most-wanted fugitives list of the U.S. Drug Enforcement Administration, with a $5 million reward for his capture.

Colombia also offered a reward of up to $800,000 for information leading to his capture. Otoniel was first indicted in 2009 in a Manhattan federal court on drug trafficking charges.

He was also known to be facing criminal charges in Brooklyn and Miami for drug trafficking and firearms charges.

Aside from Otoniel, Pablo Escobar was also one of the Colombian drug traffickers who eventually controlled over 80 percent of the cocaine being shipped to the U.S.

Escobar even landed a spot on Forbes Magazine's 10 wealthiest people in the world.

The late drug kingpin entered the cocaine trade in the early 1970s and formed Medellin Cartel. Pablo Escobar earned popularity by sponsoring charity projects and soccer clubs.

However, he turned to terror campaigns, which led the public to turn against him due to the murder of thousands of civilians. Medellin Cartel also made Colombia the main smuggling ground for marijuana.

READ MORE: U.S. Monkeypox Cases Jumps to 35; California, New York Lead the Number of Positive Cases

This article is owned by Latin Post.

Written by: Joshua Summers

WATCH: Italian Police Seize Tonnes of Colombia Gang's Cocaine - From Reuters