PARIS — Since 2011, when investigators first impounded luxury cars held by the family of Equatorial Guinea’s president, anticorruption groups hoped that France would deal a mortal blow to the injustice they believe has enriched the country’s elites while many of its citizens languish in poverty.
On Wednesday, a judge decided they would have to wait a bit longer.
Three days into the closely watched trial of the president’s son, Teodoro Nguema Obiang Mangue, on embezzlement and money-laundering charges, the presiding judge, Bénédicte de Perthuis, agreed to give the defense more time to prepare. The judge rescheduled the trial for June 19.
Mr. Obiang, known by the nickname Teodorin, is the son of President Teodoro Obiang Nguema Mbasogo, who took power in a 1979 coup and is the longest-serving head of a government in Africa. A former Spanish colony, oil-rich Equatorial Guinea has experienced a boom that started around 2004, but the gains have been far from evenly distributed; half the country lives in poverty.
The French authorities used trucks to haul away Mr. Obiang’s luxury car collection in Paris, which included two Bugattis, two Ferraris, an Aston Martin, a Maybach, a Maserati and a Rolls-Royce in 2011, suspecting that he had looted public funds.
The next year, they raided a house on the Avenue Foch, near the Arc de Triomphe. A 101-room property, the house is worth $180 million and includes two gyms, a cinema, a nightclub, a hair salon, a Turkish bath and bathrooms with gold- and jewel-encrusted fixtures, along with $50 million in furniture.
Prosecutors say Mr. Obiang amassed a personal fortune of around $115 million from 2004 to 2011, which he then used to indulge his expensive tastes. When he served as agricultural minister of Equatorial Guinea, prosecutors say, he used his influence over the timber industry — the country’s main export after oil — to line his pockets.
If convicted, he could face up to 10 years in prison, but he is not in France and it is highly unlikely he will serve his sentence.
When the judge asked Mr. Obiang’s lawyer, Emmanuel Marsigny, if his client would appear in court in June, Mr. Marsigny said he did not know, comparing Mr. Obiang’s calendar to that of France’s president. “Even François Hollande’s schedule,” he said, “is subject to change.”
While Mr. Obiang may never go to prison, “this trial must be exemplary,” said William Bourdon, a lawyer for the anticorruption group Transparency International.
“More and more states are recognizing that if we do not combat the flow of dirty money, tax evasion and corruption, we threaten the balance of public finances and the real economy,” he said. “It’s the taxpayer that pays the price in the end. There is a historical movement underpinning this trial, which gives it a powerful symbolism.”
Efforts to charge Mr. Obiang with corruption and money laundering began in 2007, when three nongovernmental organizations — Sherpa, which combats economic crimes; Survie, which supports the people of former French colonies of Africa; and the Fédération des Congolais de la Diaspora, which is combating corruption in Central Africa — filed a complaint accusing three African politicians of using public money to buy property in France illegally.
The politicians were Mr. Obiang, as well as Omar Bongo of Gabon and Denis Sassou-Nguesso of the Republic of Congo. The organizations approached Transparency International for help. Mr. Bongo died in 2009.
The government of Equatorial Guinea has fought back. It tried to halt the proceedings in France by claiming immunity for Mr. Obiang — who holds the position of first vice president of his country — but last month, the International Court of Justice rejected that appeal.
The court did, however, rule that the 101-room mansion had the legal status of a diplomatic mission. Judge de Perthuis cited lingering doubt over the legal status of the property as another reason to delay the trial.
According to Mr. Bourdon, the charges have not been supported by some in the French establishment, some of whom have significant economic and political interests in West and Central Africa. Paris remains a favored destination for African leaders, some of whom have made contributions to French political parties.
“We succeeded in braving many obstacles, notably those made by the Paris prosecutor’s office under the mandate of Nicolas Sarkozy,” Mr. Bourdon said, referring to Mr. Hollande’s predecessor as president.
He said Mr. Sarkozy’s office had gone along with “the idea that these heads of state could continue to invest in Paris with total impunity, which they have done since the end of colonialism,” adding: “This trial is a new paradigm.”
Mr. Obiang’s lawyer, Mr. Marsigny, disagreed. He said the case represented an undue intervention by French courts in the affairs of a sovereign nation. He also argued that while his client might have acquired a personal fortune, his financial dealings were never illegal in Equatorial Guinea. “His activities were not illicit — they were perfectly legal with regards to the laws of his country,” he said in an interview. The Embassy of Equatorial Guinea in Paris did not respond to a request for comment.
The United States also investigated the Obiang family’s finances.
In 2014, Mr. Obiang settled a case brought by federal prosecutors. He agreed to sell a $30 million mansion in Malibu, Calif., a Ferrari and various Michael Jackson memorabilia. Mr. Obiang “received an official government salary of less than $100,000 but used his position and influence as a government minister to amass more than $300 million worth of assets through corruption and money laundering,” in violation of the laws of both his country and the United States, prosecutors said.
In November, prosecutors in Switzerland seized luxury cars belonging to Mr. Obiang. And last month, at the request of the Swiss, the Dutch authorities seized Mr. Obiang’s 250-foot, $100 million yacht, named the “Ebony Shine,” as it was about to sail to Equatorial Guinea, according to the Swiss publication L’Hebdo. Mr. Obiang said the yacht belonged to his country’s government.