A judge in Chile is questioning seven former military officers about an attack on two students in 1986 during the government of General Pinochet.
The men are accused of involvement in setting 19-year-old Rodrigo Rojas and 18-year-old Carmen Quintana on fire during a demonstration.
Rodrigo died four days later; Carmen survived and spent years in rehabilitation.
The case was reopened after a military conscript changed his testimony.
His evidence broke a pact of silence lasting nearly three decades by the army over one of the most prominent cases of human rights abuses of Chile’s 17-year military rule.
On 2 July 1986 during a protest against the Pinochet government, a military patrol detained Carmen Gloria Quintana, a student of psychology and a young Chilean-born American photographer, Rodrigo Rojas de Negri.
The soldiers poured petrol over them and set fire to them. They then put out the fire and drove them to the outskirts of Santiago and dumped them.
Despite the seriousness of their injuries, the students managed to get help and they were taken to a hospital.
Rodrigo Rojas died four days later. He had been visiting Chile from the United States where he lived with his mother who was a Chilean political exile.
Official accounts of the incident said the two victims accidentally set themselves on fire when constructing a flaming barricade to hold back law enforcement officials.
The attack drew the condemnation of foreign governments and human rights groups in Chile and abroad.
The case was reopened this week when a military conscript, Fernando Guzman, changed his previous evidence.
He said the officers intentionally set the two teenagers on fire before abandoning them in the ditch 20km (12 miles) outside the Chilean capital, Santiago.
He said he and his family had been threatened and he had been ordered to keep silent about what had happened.
Carmen Quintana, who is a scientific attache at the Chilean embassy in Canada, said: “The truth has come late, and I hope that justice comes too. I congratulate this former conscript for his bravery, and for finding the courage to tell the truth.”
Rodrigo Rojas’s aunt, Amande de Negri told Chilean TV: “That someone would break the silence is something we always hoped for, and finally it happened.”