In mid-June of 1989, Chilean soldiers seized Marcos Quezada Yanez and hauled him away to prison. They questioned Yanez repeatedly about his political views, his friends and his family. They connected electrodes to his testicles for electric shock torture. On June 24, the current was so strong, and the prisoner so weakened, that Yanez died.

He was 17 years old.

The torture and killing of that high school boy was one of a roster of crimes alleged against former Chilean president Augusto Pinochet in a London magistrate's court today. The government of Spain set forth the charges as it opened legal arguments on its request for Britain to extradite the Chilean general for trial on charges of human rights abuses during his 17 years in power.

Alun Jones, a British prosecutor arguing for Spain, named 34 people who allegedly were tortured or killed at Pinochet's direction in the last two years of his rule. Six victims were women. Spain said Chilean authorities had subjected the prisoners to electric shock, beatings, starvation, sleep deprivation and "suspending . . . in a state of acute physical discomfort."

Pinochet, 83, who seized power in a violent coup in 1973, was known by the titles "general" or "president" during his reign. But today, under house arrest in Britain pending a decision on the extradition request, he was referred to in the legal papers by a less exalted title: "the fugitive."

Nearly a decade after he left office, Pinochet's polarizing effect on Chilean politics remained vividly clear as hundreds of pro- and anti-Pinochet demonstrators exchanged shouts and chants in the rainy street outside the court building.

Pinochet, who has described himself as "a warrior," has fought a vigorous legal battle to go home to Chile since he was first placed under arrest 11 months ago while here for medical treatment. His chief argument is that the British and Spanish courts have no criminal jurisdiction over things he may have done in Chile. He lost that argument this spring when Britain's highest court ruled--in a key new international precedent--that former heads of state accused of human rights abuses can be brought to trial in any country that has ratified the International Convention against Torture.

Britain accepted that treaty on Dec. 7, 1988. The judges said Pinochet can only be extradited from Britain for crimes committed after that date. That is why Spain today cited only the 34 cases of torture alleged between late 1988 and March of 1990, when Pinochet was forced to run for election--and lost.

Pinochet's lawyer made an extensive argument that 33 of the 34 charges could not be considered in the extradition case because Spain had not identified these victims in earlier court papers. This point may have no practical impact because even a single charge can justify extradition.

The only specific charge that lawyers for Pinochet responded to was the killing of Yanez, the 17-year-old. The defense argued that Pinochet cannot be tried on this charge because "it is not conduct for which [Pinochet] is alleged to be responsible either as principal or secondary party."

But the prosecutors said Pinochet was accused "not on the basis that he inflicted the torture itself, but as a secondary party, counseling and procuring."

CAPTION: Ana Gonzalez displays a photo of relatives lost during the Pinochet era at a rally in Chile yesterday.