Jara, a leftist activist, was detained following the overthrow of the South American nation's leftist president Salvador Allende in a CIA-backed coup in September 1973 that launched the rule of dictator Augusto Pinochet.
The singer, who has inspired musicians as wide-ranging as U2 and Bob Dylan, was rounded up with thousands of other dissidents into the Estadio Nacional in Chile's capital Santiago, where he was beaten, tortured and shot dead.
Pedro Pablo Barrientos Nunez, who has been living in the US since 1989 after fleeing Chile when Pinochet's rule ended, was a 24-year-old lieutenant at the Estadio Nacional, and one of those in charge of the detainees.
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One witness, an army conscript, told the court via videotaped deposition that he heard Barrientos tell someone he had fatally shot Jara. No one offered an eyewitness account of the shooting.
Barrientos, now 67, sat motionless when the verdict was read in the courtroom.
He refused to comment to reporters after the trial, but his lawyer Luis Calderon said they were going to explore options for appeal.
Jara's 88-year-old widow Joan and her daughters Manuela and Amanda were joyful and tearful after the verdict was read.
"Today was for Victor. This was the first sign of justice for his case and it occurred here in the United States," Joan Jara said.
Kathy Roberts, a lawyer for the Center for Justice and Accountability, a San Francisco-based rights group that filed the case on behalf of the Jara family and estate, said she was pleased with the outcome.
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"We hope the US government will take notice of the Chilean government's request for extradition," Roberts said.
Barrientos is facing criminal charges in Chile. The US government has so far not responded to the request for extradition.
The verdict could call into question his US citizenship, if authorities find he lied on his immigration application about his past. He could then be deported back to Chile, according to lawyers working on behalf of the Jara family.
Pinochet ruled Chile until 1990, installing a regime that killed some 3,200 leftist activists and other suspected opponents.
He died in 2006 at age 91 without ever being convicted for the crimes committed by his regime.
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