Brazilian billionaire on trial for insider trading
The trial has begun in Rio de Janeiro of the Brazilian tycoon, Eike Batista, who was once named as one of the world's richest people.
He faces charges of insider trading and if convicted could be the first person in the country to go to prison on such charges.
Mr Batista saw an estimated $30bn fortune plummet over the last two years.
His holdings in oil, mining, logistics and shipbuilding have also diminished.
Mr Batista faces charges of having manipulated market charges in the sales of shares of two of his companies.
They include the OGX oil exploration and production unit which filed for bankruptcy last year.
Prosecutors accuse Mr Batista of trading on the stock of OGX with knowledge about key petroleum fields' lack of economic viability - a charge he rejects.
Mr Batista faces fines and up to 13 years in prison although under Brazilian law he could get a lighter sentence as a first-time defendant.
A complex and lengthy appeal process also makes it likely a jail term could be delayed or not imposed because the statute of limitations runs out.
Correspondents say the trial marks a shift in attitude towards the rich and powerful, but Brazilians will want to see if the justice system can shake off its reputation for lengthy delays and leniency toward those accused of white-collar crime.
Earlier this week, 23 people, including chief executives of some of the largest construction companies in Brazil were arrested in relation to a corruption scandal at the state-run oil company, Petrobras.