Four former policemen have gone on trial in Brazil for the murder of a presidential campaign treasurer and his girlfriend nearly 17 years ago.
Paulo Cesar Farias' bodyguards are accused of failing to prevent his and Suzana Marcolino's deaths.
The case was shelved in 2002 for lack of evidence, but a Supreme Court ruling allowed it to be reopened.
Mr Farias was accused of running a corruption ring while President Fernando Collor de Mello was in office.
He had been the treasurer of Mr Collor de Mello's successful presidential campaign in 1989.
The prosecution argues that Mr Farias was murdered in 1996 because of his role in the large-scale corruption scheme that traded in federal government influence.
In 1992, Brazil's then-President Collor de Mello resigned after being found guilty of corruption by the Senate and then impeached by the Congress.
The criminal case against the president was dismissed, but a judge ordered Mr Farias' arrest for tax evasion.
He fled the country, but was caught in the Thai capital, Bangkok, in 1993.
Mr Farias had been serving a suspended prison sentence and was on trial for other crimes, when his body was found next to Ms Marcolino's in the north-eastern city of Maceio.
His four private bodyguards had been outside the room he shared with Ms Marcolino, but said they had not heard the two shots that killed the pair.
Investigators said Mr Farias was killed by his girlfriend, who then committed suicide.
But a ballistics report later disputed that theory, saying she could not have fired the shots.
The case against the four guards and a fifth man was shelved for lack of evidence in 2002.
But nearly a decade later the Supreme Court ruled that both victims had been murdered, despite defence appeals which argued the deaths had been a murder and a suicide.
Correspondents say this is one of the most mysterious murder cases in Brazil.
Even if the former policemen are found guilty, questions will still remain about who pulled the trigger or possibly ordered the deaths.
Investigators are yet to find what happened to the money Mr Farias allegedly made from the scheme.