A former Spanish minister was quizzed Thursday by a local judge investigating his alleged role in 12 deaths during Spain's transition to democracy after dictator Francisco Franco died in 1975.
In a five-hour video conference session at Argentina's embassy in Madrid, Rodolfo Martín Villa, 85, who served as interior minister in the late 1970s, answered questions from investigating magistrate María Romilda Servini de Cubría in Buenos Aires.
Servini is investigating the deaths of 12 people who were shot dead by police and ultra-right-wing groups at a time when Spain was beset by attacks by groups on both political extremes as it struggled towards democracy.
Martín Villa has protested his innocence.
Servini opened her investigation in 2010 into allegations of human rights violations and genocide in Spain during the Franco regime and the turbulent years that followed.
The investigation is part of a lawsuit filed by associations representing families of victims killed during the 1939-1975 dictatorship, crimes which cannot generally be tried in Spain due to a 1977 amnesty law.
She based her probe on the principle of universal jurisdiction which allows judges to try serious rights abuses committed in other countries.
Five of the victims were shot dead by police as they raided a church where protesting workers were sheltering in the northern city of Vitoria in 1976 when he was minister for trade union relations.
He also faced questioning over the deaths of seven other people in Madrid and the northern Navarre region at the hands of state security forces when he was interior minister between 1976 and 1979.
Martín Villa has said he was willing to cooperate with the probe to prove his innocence. To back his case he submitted letters of support from veteran politicians and union leaders, including Spain's last four prime ministers.
All of them insisted he "always acted with a total commitment to defend the rule of law and reform state security forces," his defence team said in a statement to AFP.
The judge now has 10 days to decide whether to charge him and request his extradition.
"The complaint is a decade old. If Villa is prosecuted, it would be a historic event," Julieta Bandirali, the lawyer in charge of the case in Argentina, told AFP.
Deputy Prime Minister Pablo Iglesias, who heads the radical left-wing Podemos and has often criticised the "silence" over crimes committed during that period, also hailed the hearing.
"Today a historic step is being taken in Argentina towards justice and against impunity. Rodolfo Martín Villa will answer for crimes against humanity," he tweeted.
The magistrate had tried to have Martin Villa extradited in 2014, but the Spanish authorities refused.
In Buenos Aires, Eduardo Fachal, lawyer for the prosecution said that if Servini decides not to prosecute, they would appeal as they wanted to see the case "through to the end".
Previous attempts to bring Franco-era officials to justice in Spain have been blocked by the amnesty agreement signed by political leaders after Franco's death.
The agreement was seen as essential to avoid a spiral of score-settling as they tried to unite the country and steer it towards democracy.
Spanish authorities still invoke the amnesty law in refusing to investigate alleged atrocities during the Franco era, despite demands by the United Nations that it be scrapped.