A court in Chile has decided to reopen an investigation into the death of Ronni Moffitt, a US citizen killed by secret agents in 1976.
She was in the car of former minister Orlando Letelier when it exploded in Washington DC, killing both of them.
Ronni Moffitt, Letelier's 26-year-old assistant, and her husband were given a lift by him after their car broke down.
An FBI investigation blamed the Chilean secret police, Dina, for the attack.
The Appeals Court in the Chilean capital, Santiago, has now revoked a judge's order to close the Moffitt case.
Judge Mario Carroza argued last year that the attack had taken place abroad, killing a foreign citizen, and therefore should not be investigated in Chile.
But the court said the investigation should be reopened because those behind the attack were Chilean citizens.
The head of the Chilean secret police was convicted in Chile in 1993 over Letelier's assassination.
In 1978, a US citizen, Michael Townley, was extradited from Chile to the US where he confessed to carrying out the bombing.
The FBI investigation found out that Chilean secret agents hired right-wing Cuban militants in the US to carry out the attack.
Two days before the explosion, they taped a bomb underneath Letelier's car and later activated it by remote-control.
Ronni Moffitt's husband, Michael, was in the back seat of the car and survived the explosion.
Orlando Letelier was foreign minister in the government of left-wing president Salvador Allende.
He was one of the first cabinet ministers arrested in September 1973, after the military coup led by Gen Augusto Pinochet
After a year in prison, he was allowed to leave the country. Mr Letelier was invited to work at the Institute of Policy Studies, a left-wing think-tank, in Washington.
He had been there for a year when he was killed, on 21 September 1976.
Before the attack, Letelier's wife, Isabel, had received anonymous phone threats telling her her husband was in danger.
"I remember one very specifically because it was really short," she said. "They called me and said, 'Are you Ms Letelier?' I said, 'Yes' and they laughed and said, 'No, you are his widow.'"
Although CIA evidence showed the Chilean leader had direct knowledge of the assassination, Pinochet was never charged.