The arrest in Spain of Argentine Rodolfo Almiron has brought back memories of a dark chapter in Argentina's history - that of the death squads that targeted left-wingers before the 1976 military coup.
Mr Almiron is wanted in his home country for murders committed in the 1970s by the Argentine Anti-Communist Alliance, or Triple A - a far-right organisation responsible for hundreds of deaths between 1973 and 1975.
It was set up during Juan Domingo Peron's third and last presidency by Jose Lopez Rega, then minister for social welfare. It continued to operate under the government of Peron's widow, Isabel, during which period most of the killings took place.
At the time, the Peronist movement was bitterly divided between leftist and rightist members.
Lopez Rega - known as "the Wizard" and sometimes described as "Argentina's Rasputin" - is said to have recruited followers from the police, the military, trades unions and right-wing sectors of Peronism.
His main collaborators are said to have been the then police chief Alberto Villar, police superintendent Jose Ramon Morales and former police officer Rodolfo Almiron.
On 21 November 1973, the Triple A carried out what was to be the first of hundreds of attacks against what it perceived to be its opponents, placing a bomb under the car of Senator Hipolito Solari Yrigoyen.
The bomb did not kill him, and the group made another failed attempt on his life in 1975.
Despite the unsuccessful debut, an official commission later found documentary evidence to show the group killed 428 people, although some estimates suggest the number is closer to 1,000.
Lopez Rega used the generous budget he enjoyed as a government minister to buy huge amounts of weapons.
When he resigned on 11 July 1975 - after being accused by the Peronist Party of instigating the Triple A - he was appointed special ambassador to Spain, and fled there.
An arsenal including machine guns, grenades and snipers' guns were later found in his office in the ministry.
The Triple A was dismantled although the military governments that held power between 1976 and 1983 shared and targeted many of the same "enemies".
Lopez Rega was extradited to Argentina in 1986. He died three years later in a Buenos Aires jail awaiting sentence at the age of 73.