The Venezuela authorities say they are opening a corruption investigation into one of the country's most influential political figures, the former oil minister Rafael Ramírez.
Mr Ramírez ran the state oil company, PDVSA, for 12 years until 2014.
Last week he was sacked from his post as ambassador to the UN, and left the US for an undisclosed third country.
He has been tipped as a potential presidential candidate in next year's elections. He denies any wrongdoing.
"We have decided to open a criminal investigation of Rafael Ramírez, ex oil minister and ex president of PDVSA," said Chief Prosecutor Tarek Saab in a televised address.
He said the Panama Papers, leaked last year, held compromising information about Mr Ramírez and his cousin Diego Salazar, who was arrested this month.
The investigation into Mr Ramírez's activities appears to be part of a corruption purge at PDVSA. Sixty-five people have been arrested there for alleged corruption in the last few months.
In recent weeks, Rafael Ramírez publically criticised the current administration's handling of Venezuela's deep economic crisis saying he had anticipated it but was ignored.
In a newspaper, he wrote: "I am disappointed that no kind of constructive criticism is allowed.
"Is it ethical to remain silent?"
Between 2004 and 2014 Mr Ramírez became the most visible face of Venezuela's late socialist leader Hugo Chávez's oil sector nationalizations which boosted state control over the industry.
The oil bonanza of that period largely financed the social programmes that cemented Mr Chávez's power.
Mr Ramírez was very close to Mr Chávez and was on hand in the last moments before he died.
But he clashed with Mr Chávez's successor, Nicolás Maduro, and was named foreign minister and then sent to New York as a United Nations ambassador.
There his profile was lowered, although he vehemently defended Venezuela in the UN from what the Maduro administration considered "attacks" led by the US.