Isabel dos Santos has been named as a suspect in an investigation over alleged mismanagement during her time as chairwoman of Sonangol, Angola’s state oil company, a position she was appointed to by her father, ex-President Jose Eduardo dos Santos.

Four others were also named on state TV late Wednesday by the country’s prosecutor general, Helder Pitta Gros. One of the suspects, the director of private banking at Lisbon-based lender EuroBic, Nuno Ribeiro da Cunha, was found dead at his home in Portugal late Wednesday, Portuguese newspaper Jornal Economico said on its website.

The inquiry covers the period that Dos Santos served as chair of Sonangol, from June 2016 to November 2017, when she was fired by her father’s successor, Joao Lourenco.

The announcement comes days after the International Consortium of Investigative Journalists released a series of documents showing how Africa’s richest woman built a multibillion dollar business empire via mostly questionable deals involving state assets during her father’s 38-year tenure. Earlier this month, a court in Angola froze her assets and bank accounts.

Dos Santos, who has been living outside Angola since 2018, was not immediately available for comment. She has previously denied wrongdoing.

Her brother Jose Filomeno, the former head of Angola’s $5 billion sovereign wealth fund, has been on trial since December for his involvement in a $500 million transfer from the central bank to an account in the U.K. during the final days of his father’s rule.

Authorities would like the suspects to come in voluntarily, but international arrest warrants may be considered if they continue to refuse cooperation, Pitta Gros said. They may also try to block Dos Santos from selling assets and shares held in Portugal, the former colonial ruler, and elsewhere if they were bought with money that was transferred illicitly from Angola, he said.

“If we get evidence that the investments were made with money taken illicitly out of the country we will do everything so that she doesn’t dispose of those assets,” said Pitta Gros, who arrived in Portugal on Thursday to ask for help with the investigation.

Among those named by the prosecutor are Mario Leite da Silva, an executive with close ties to Isabel dos Santos and chairman of Banco de Fomento Angola, and Paula Olveira, the owner of Dubai-based consulting firm Matter Business Solutions. Da Silva stepped down Thursday, BFA said in a statement following the prosecutor’s announcement. Isabel dos Santos holds a 25% stake in Angola telecommunications company Unitel, which has a majority stake in BFA.

EuroBic bank said in a separate statement that Dos Santos has decided to sell her 42.5% stake.