Chilean authorities have arrested four former army officers accused of involvement in the murder of singer-songwriter Victor Jara.
Jara was killed days after the coup that brought General Augusto Pinochet to power in September 1973.
More arrests are expected after a judge last week indicted eight ex-officers, including one who lives in the US.
Jara's widow, Joan Turner, has urged the US to extradite Pedro Barrientos Nunez. He has denied any involvement.
On 28 December, Judge Miguel Vazquez accused Mr Barrientos, a former lieutenant, and Hugo Sanchez Marmonti, an ex-colonel, of homicide, while the other six were accused of complicity to commit murder.
On Wednesday, four of the men, including Mr Sanchez Marmonti. handed themselves in to the authorities.
The judge has said he will request Mr Barrientos's extradition from Florida, where he now lives.
Joan Turner Jara, originally from Britain, said on Wednesday that the charges against the former officers were " a message of hope" but that much remained to be done to ensure justice not only for her husband's case but for all the victims of Chile's military dictatorship.
"If Victor's case serves as an example, we're pushing forward in demanding justice for Victor with the hope that justice will follow for everyone," she told reporters.
Victor Jara, who was a member of the Chilean Communist Party, was one of the best-known victims of Gen Augusto Pinochet's coup.
In the 1960s he wrote protest songs against the ruling elite of his country and was a supporter of President Salvador Allende who was toppled and died in the military uprising.
Jara, 38, was abducted on 11 September from a university in Santiago.
He was taken to a sports stadium in Santiago which had been turned into a makeshift prison and torture centre.
He was tortured, electrocuted and had his wrists and hands broken. On 16 September, he was machine-gunned to death.
In June 2009, his body was exhumed as part of an investigation to clarify the circumstances of his death.
Six months later, thousands people paid their final respects to the folk singer, who was reburied after a three-day wake.
More than 3,000 people were killed or went missing during military rule in Chile, from 1973 to 1990.