The billionaire Congo-born art collector Sindika Dokolo has died at age 48 after a scuba diving accident in Dubai.

The family has not yet released a statement, but his wife, Isabel dos Santos, who is Africa’s richest woman, posted a caption-less picture of her with her husband and their child to Twitter yesterday.

At the time of his death, Dokolo was under investigation for allegations of corruption. His Angola-based assets were frozen earlier this year as the government moved to recoup allegedly embezzled money from Dokolo and his wife, totaling $1 billion. According to the Angolan government, Dokolo had been making one-sided deals in the diamond industry that was effectively robbing the country.

Congolese politician Michée Mulumba expressed his sadness at the news of Dokolo’s death. “It was during a scuba dive that you left for eternity,” he said. “A habitual activity that tore you from your fight, from your loved ones.”

Dokolo was born the Congolese capital Kinshasa in 1972, and he was raised in an elite family between Belgium and France. His father, Augustin Dokolo, was a millionaire and an avid collector of African art. Sindika went on to become an ardent supporter of African arts as well, amassing a collection of more than 3,000 contemporary artworks by artists from the continent and its diaspora, including those by Yinka Shonibare, Zanele Muholi, and William Kentridge.

More recently, Dokolo had been working to track down historic looted cultural property and return it to the continent. In an interview with Artnet News last October, Dokolo explained his unique approach to restitution: “We confront the current owner and we offer them two options: Either we go to court based on the evidence that we have [about the looted art], which means reputational damage, or we pay an indemnity, which is not the current market price but the price they paid when they acquired it.”

At that time, Dokolo and his teams in Brussels and London had successfully tracked down and restituted 15 pieces of cultural heritage.

Chokwe Mask that went missing from the Dundo Regional Museum in Angola during the civil war. The mask was returned to the Angolan authorities after the exhibition of Dokolo’s collection at BOZAR – Centre for Fine Arts.

Despite his work in the cultural field, Dokolo’s own reputation was facing serious damage as he amid the allegations of widespread corruption in Angola. Documents that came to light as part of the Luanda Leaks earlier this year, showed how Dokolo had made millions via Angola’s state diamond company, Sodiam.

Dos Santos personally had control over state companies touching Angola’s land and oil, diamonds, and telecoms industries, which had been handed to her by her father, former Angola president José Eduardo dos Santos. Isabel was accused alongside other members of her family of corruption in the resource-rich nation. Angola had frozen their assets earlier this year and the family was living in exile in Dubai.