MANAGUA, NICARAGUA -- Elbio Fernandez sits in a chair in the living room of his modest home in a residential neighborhood of the capital and remembers his eldest daughter.

Framed pictures of her hang on the walls and stand on a shelf in an alcove. A couple of the photographs, taken at Christmas 1977, show her with her 2-year-old daughter, Claudia.

Idania de los Angeles Fernandez was a 26-year-old mother and an idealistic member of the Sandinista National Liberation Front when she was killed in April 1979 by the National Guard of Anastasio Somoza, then still the country's ruler. "We still suffer," said the father. "There's not one day that I don't remember my daughter."

The death of Idania has marked Elbio Fernandez, 61, a middle-class businessman who formerly worked for an American engineering company in Dallas and Latin America. Many members of Managua's shrinking middle class oppose the Sandinistas, who came to power after the July 1979 revolution that overthrew the Somoza dynasty.

But even though Fernandez shares some of the widespread complaints about Sandinista economic mismanagement and would like to see a "social democratic system" in Nicaragua, his experiences have put him solidly on the side of the Sandinista revolutionaries and resolutely against the insurgency being waged by U.S.-backed Nicaraguan rebels, known as contras.

"I gave a daughter to the revolution," Fernandez said. "I am with the revolution."

The National Guard, which killed his daughter, now provides the leadership for the contras, he said. "These people are in the contras. How could I support them?" he asked. "I can never forget what they did."

A short, stocky man with thick eyeglasses and close-cropped white hair, Fernandez said he tried in vain to dissuade Idania from joining the revolutionaries and leaving her child in his care, but that eventually he embraced her cause.

Idania's Sandinista sympathies began when she was a high school student in Managua and intensified when the family moved to Panama in 1972, he recalled. At the University of Panama, she studied economics and public administration and was recruited by the Sandinistas, some of whose leaders lived in exile in Panama City for a time, Fernandez said. He said that his daughter was influenced by Ernesto Cardenal, now the Sandinista minister of culture, and that at one time she helped provide security and safehouses for top comandantes such as Daniel Ortega, now president.

In 1977, Fernandez said, Idania decided to devote her life to the revolution and underwent several months of training in Cuba, where she became a demolition specialist. In 1978, he said, she joined the fighting on the southern front, the border with Costa Rica, and was injured in the left hand by a defective mortar round.

She was hospitalized in Costa Rica, where she identified herself to authorities only by her "combat name" of Angela, according to newspaper clippings of the period.

After Idania had recovered, Fernandez said, she returned to Nicaragua clandestinely in March 1979 and made her way to the city of Leon. There she was responsible for trying to organize an insurrection, according to Sandinista literature.

On April 16, 1979, Idania was attending a meeting in a house in Leon with five other Sandinista leaders, including a Mexican woman, Fernandez said.

National Guardsmen raided the house and killed the four men on the spot, he said, but arrested the two women and took them to National Guard headquarters. There, Fernandez said, his daughter was tortured for several hours and, he implied, raped, before she and the Mexican woman were shot to death.

The government claimed at the time that all six were killed in a firefight at the safehouse, but Fernandez said he had found out that was a lie. "They were killed in cold blood," he said.

Compounding Fernandez's anguish is the belief that he knows who was responsible for the killing. The military commander of Leon at the time, a National Guard colonel, was a classmate of Fernandez in elementary school in Managua, he said. "They called him 'The Tiger,' " Fernandez said. "Now he's living in Miami."

Fernandez and his wife now spend their time with the granddaughter, who at 12 is attending the American School here. On Fernandez's frequent business trips abroad, he carries a briefcase that contains reminders of his daughter's life. There are snapshots from happier times, such as that Christmas in 1977, and a photograph of Idania, wearing a green Sandinista uniform and holding her wounded left hand, being escorted out of Nicaragua's southern jungle into Costa Rica. A tattered American newspaper clipping tells of his daughter's death, dating from interviews he gave while working in Dallas in 1979.

A photograph obtained later shows his daughter's body, with a bullet wound in the forehead. There is also a letter, dated March 8, 1979, which Idania wrote to her daughter and left for her in care of her father.

"Dear little daughter," it says. "The Revolution demands everything from each one of us . . . . My deepest desires are that some day in the not too distant future, you will be able to live in a free society -- where you will be able to fulfill yourself as a true human being, where men will be brothers and not enemies . . . "