General Pinochet's argument for being released is that he entered Britain on a diplomatic passport, giving him immunity from arrest or from prosecution. But diplomatic immunity did Soria no good when General Pinochet's military hitmen kidnapped, tortured and killed him, breaking his neck on 15 July 1976.
The 54-year-old veteran of the Spanish Civil War was a Spanish citizen, a United Nations diplomat serving at the Santiago regional headquarters of the UN's regional body, Cepal. He edited the publications put out by the commission's demographic department.
He was driving home in Santiago in his official beige Volkswagen, with diplomatic number plates, an hour or so earlier than usual because he had a bad headache. He was carrying his diplomatic passport. Soria was one of many Spanish victims of General Pinochet's 17-year military rule and his case has been central to Spanish judge Baltasar Garzn's attempts to bring the former dictator to trial in Spain on charges of genocide, terrorism and torture. But General Pinochet's claim to the same diplomatic immunity that should have protected Soria has added an ironic twist.
Under heavy police protection in her Santiago home after several death threats against her and one of her school-age daughters, Carmen Soria, a 38-year-old separated mother of three, described to the Independent on Sunday how her father died. She said her information came from witness reports, including statements from Soria's killers.
"He was at a crossroads five blocks from our house in the Las Condes district when four apparent policemen flagged him down on a supposed traffic offence. It emerged later they were military officers from the so-called Mulchen brigade of the military-run DINA secret police. They tortured him for hours.
"When my mother reported him missing, she was told he was being held in the El Salto barracks. When we went there, they told us he'd never been detained, but that his car had crashed into the canal, the Carmen canal no less, and that they would drain it and look for the car the next day."
Military officers handed over Soria's woollen scarf and his passport, claiming they had found them by a roadside. Police said they found his body in the car in the canal. They said there had been two empty bottles of pisco, a local schnapps, in the car, suggesting he had been drunk. The family never saw his body.
A public coroner ruled he had died in an accident, but an American coroner called in by Ms Soria's mother, Laura Gonzalez Vera, determined that his neck and several ribs had been broken.
After a long fight by the mother, who lives in Spain, and Ms Soria, who stayed, it was not until Chile returned to democracy in 1990 that the case was clarified, partly thanks to the Truth and Reconciliation Commission created by the civilian president Patricio Aylwin. It was only in 1995, almost 20 years after the murder, that a judge tried and convicted six military officers or soldiers with torturing and killing Soria.
But the only two who showed up for the trial, DINA agents Guillermo Salinas and Patricio Quilot, were released on a bond of 10,000 pesos (pounds 13) each after the judge ruled that they were covered by an amnesty law passed by General Pinochet. At least two of the other officers are still in active service.
Salinas and Quilot described in court how they had used a Nazi-era technique known as desnucar - literally de-necking - jamming Soria's head between two steel steps then stomping on his back. The regime reportedly suspected Mr Soria - an anarchist during the Spanish Civil War - of using his diplomatic position to establish and maintain links with underground communists in Chile.
The Soria family - Carmelo was the grandson of Arturo Soria, a distinguished Madrid architect whose memory is honoured in the Spanish capital - had received confirmation of those facts from former UN secretary-general Boutros Boutros Ghali and his successor Kofi Annan, Ms Soria said. Spanish judges eventually took on the family's case and it became an important factor in the extradition request for General Pinochet.
Ms Soria at first appeared at some of the demonstrations in favour of his detention. But she immediately received death threats, presumably from the general's supporters.Reuse content