Four alleged members of an Irish crime gang and five other defendants went on trial in France on Monday, accused of trafficking rhino horn and ivory to markets in East Asia.
French prosecutors started an investigation in 2015 after police found elephant tusks and €32,800 ($38,900) in cash in a BMW during a random motorway traffic inspection.
Prosecutors in the town of Rennes say the occupants of the car, who claimed they were antique dealers, were members of the Rathkeale Rovers, an Irish crime gang.
The nine defendants, who include people of Chinese and Vietnamese origin, face up to 10 years in jail and heavy fines, although two of those charged are on the run.
"We're hoping for heavy sentences including fines to dissuade people from taking part in smuggling activities that encourage the cruelty of poaching," Charlotte Nithart, head of French anti-poaching charity Robin des Bois, told AFP.
Ms Nithart, who was in court as an observer, said the case files and the first day of hearings had underlined how Europe, and European auction houses, played a role in supplying East Asia with horns and tusks.
"What you can see in the intercepted telephone records is that the supply comes from lots of different towns in France and around Europe," she said. "The networks are well structured."
Many of the objects are old ornaments and antiques, but the seizure by police of tusks that are less than 20 years old suggest that parts from recently poached animals are also being traded.
As part of their investigation, French police found that tusks and rhino horns were being turned into powder, flakes and other objects on French soil before being exported to Vietnam and China.
Vietnamese defendant David Ta, 51, owner of an export company in the Paris region, denied illegally trafficking protected animals, despite the discovery of 14 tusks on a pallet at his home.
"I'm a collector. It's a passion," Mr Ta told the court.
Four suspected members of the Rathkeale Rovers – Tom Greene, Richard O'Riley, Edward Gammel and Daniel MacCarthy – are accused of supplying horns and tusks to exporters in France with links to China and Vietnam.
An exceptionally large horn weighing almost 15 kilograms, which was seized from the gang during the investigation, would have been worth about $15 million at Asian market prices at the time, Robin des Bois said.
The organised crime group from County Limerick in western Ireland "have many activities, but what is of interest to us is their speciality in trading rhino horns", Ms Nithart said.
They have been linked to thefts from museums and private collections.
There were suspicions that they had been involved in the 2017 killing of a white rhino in Thoiry zoo outside Paris. The animal's horn was hacked off in an overnight raid.
The group is also known to be behind a pan-European scam in selling counterfeit tarmac for resurfacing private driveways.
The Rathkeale Rovers were the focus of a joint investigation by European police in 2010, which led to 31 people being arrested, including for the theft of rhino horns, the Europol police agency's website says.
Two members were arrested in the US in 2010 after paying undercover investigators in Colorado about $17,000 for four black rhino horns.