Lima, Peru (CNN) -- Family members requested a humanitarian pardon Wednesday for former Peruvian strongman Alberto Fujimori, saying he should be released from prison because of health problems.
The 74-year-old Fujimori is serving four concurrent sentences, the longest of which is 25 years, for corruption and human rights abuses.
He underwent surgery September 19 for a recurring lesion in his tongue and returned to the clinic nine days later because of problems with scarring of the wound, the state-run Andina news agency reported.
"This request is argued on the basis of medical facts," said Keiko Fujimori, the former president's daughter, who was quoted by Andina.
Family members say the ex-president, who has suffered from mouth cancer, will die if he remains a prisoner.
"We will have to evaluate if the conditions of imprisonment, which in any light are different than what prisoners in the country normally receive, affect the health of Mr. Fujimori," said Julio Arbizu, Peru's top anti-corruption prosecutor. "That does not seem to be the case."
In recent weeks, word of the Fujimori family's plans to request a pardon has riled political opponents. Human rights activists have said granting a pardon to the former strongman would be an insult to victims of his regime, Andina reported.
Alberto Fujimori is a polarizing figure in Peru, the country he led from 1990 to 2000. His strong hand is credited with defeating the Shining Path terrorists who destabilized the country, and his austere economic policies reined in hyperinflation.
But stability had a cost, which in his case was an authoritarian streak that included the killing of civilians. After winning a third term whose constitutionality was challenged, he was finally brought down by an Andean-sized corruption scandal.
In 2009, a special supreme court tribunal sentenced him to 25 years in prison for authorizing the operation of a death squad responsible for killing civilians.
In separate trials, Fujimori was found guilty of breaking into the home of a former spy chief to steal incriminating videos, taking money from the government treasury to pay the spy chief, authorizing illegal wiretaps, and bribing congressmen and journalists.
As his decade-long presidency neared its end in 2000, Fujimori fled Peru for Japan, where he holds dual citizenship because his parents were born there. Japan refused to honor Peru's request to return him for trial, saying its nationals should be subject to Japanese law and pointing out the two countries have no extradition treaty.
He attempted to resign from the presidency by fax from Japan, but Peru's congress refused to accept it, instead declaring him morally unfit to govern.
He arrived in Chile in 2005 in what some saw as a possible attempt to return to Peru and seek office there in 2006. He was under house arrest for six months in Chile and was extradited to Peru in 2007.
The former leader still has both fierce critics and strong supporters in the South American country.
His daughter Keiko lost a bid for president last year. Rallying cries in support of her father were common among crowds at her campaign events.
Now that she and her siblings have filed paperwork with Peru's justice ministry requesting a pardon, President Ollanta Humala -- the man who defeated her at the polls -- will have the final say.
His decision could have wide-ranging consequences. Political analysts say a decision in favor of the Fujimori family could change Peru's political panorama, converting old rivals into allies.
Journalist Maria Elena Belaunde and CNN's Mariano Castillo contributed to this report.