From torture and murder in the Netherlands and Serbia to an unprecedented web of corruption in Belgium, the Sky ECC investigation has shone a light into some of Europe's darkest corners.
Sky ECC was a secure messaging app once prized by underworld drug barons. But, after it was cracked by investigators in 2021, it has brought some to their downfall.
Police from Belgium, France and the Netherlands are now sifting through a vast trove of messages sent within the secretive drug smuggling gangs, and they have begun to make arrests.
"It was as if we were sitting at the table with the criminals," said Catherine De Bolle, executive director of Europol, the EU police coordination agency.
Last year, Belgian police tracking what was already reckoned to be a huge drug smuggling operation in the North Sea port of Antwerp noticed concentrated activity on the covert network.
More than 48 people were arrested in a series of raids on March 9, 2021 and 200 premises were searched, thanks in part to evidence in messages culled from the Sky ECC records.
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Antwerp is reputed to be the principal port of entry to Europe for cocaine from Latin America -- 90 tonnes were seized last year alone.
In parallel, French investigators were examining an "undeclared" communications network hosted on servers in France, culling more criminal data.
More than a year and a half later, detectives on both sides of the border agree that the Sky ECC probe marked a turning point in the war against the drug gangs.
'House of horrors'
Eric Snoeck, director general of Belgium's Federal Judicial Police, told AFP that authorities have their hands on more than one billion Sky ECC messages.
"We've made use of a relatively small proportion of the available evidence," he said. "It's work that is ongoing and will take years to complete."
Since the breakthrough, more than 1,200 people have been detained for questioning in Belgium and 510 criminal case files opened and informed by Sky ECC data.
This week, messages discovered on the covert network allowed police to launch a cross-border operation to dismantle a "super-cartel" thought to control a third of Europe's cocaine trade.
Officers in five countries arrested 49 suspects, including six alleged drug barons based in Dubai.
Antwerp police alone have opened 257 case files based on the new evidence.
The investigations are making progress tracking down drug dealers, but they have also shown how deeply gangs have penetrated Belgium's society and economy.
In September, Belgian Prime Minister Alexander De Croo announced reinforcements for the police investigative service and warned that organised crime's reach extends far beyond the country's ports.
And if the scale of the networks is vertiginous, their violence is disturbing.
"They have imported into Europe behaviour that we thought contained in Latin America," said Remy Heitz, general prosecutor at the Paris court of appeals.
"Terror, murders, people being executed on live video and shared with laughing viewers. That is how they manage these businesses."
Snoeck describes "a previously completely unheard-of level of violence" and cites the discovery of shipping containers equipped as torture chambers in the Netherlands.
"For a few thousand euros, for a contract that wasn't fulfilled, they murder without hesitation -- sometimes after hours of agony -- people they were working with a few hours earlier," Snoeck said.
Text messages exchanged on the encrypted network allowed investigators to find a "house of horrors" in Serbia near the capital Belgrade where victims were dismembered and fed into a meat grinder.
While most senior figures arrested so far were living in Dubai, the Western Balkans has also proved a hotspot for the gangs.
After English, the most common language used on Sky ECC was Albanian, investigators found.
Data from Sky ECC, which was marketed by now-defunct Canadian firm Sky Global, has been shared with authorities in 22 countries, including Colombia and Brazil.
Investigators who were already confronted by the Moroccan-Dutch "Mocro-Maffia" and southern Italy's 'Ndrangheta Mafia now know that Latin American cartels are implanted on European soil.
"I'm very worried," a French magistrate told AFP, speaking on condition of anonymity.
"We're underestimating the danger of these networks in terms of destabilising the state and spreading violence to all corners of society."