GUATEMALA CITY -- Fernando Garcia, a 25-year-old student and union leader, had just finished negotiating a collective labor agreement at the factory where he worked when he "disappeared" on Feb. 18, 1984.

According to his wife, Nineth, he was picked up on a Guatemala City street by uniformed members of a police special operations unit and driven away in a car. She never saw him again.

The incident immersed her in the netherworld of Guatemala's political disappearances, a practice that began here in 1966 and soon became part of the lexicon of political violence in other Latin American countries.

It is generally acknowledged that human rights violations have decreased significantly in Guatemala during the past couple of years. But despite the passing of the military regimes that committed abuses as they fought a Marxist-led insurgency, the issue continues to gnaw at the 18-month-old civilian government of President Vinicio Cerezo, who has resisted calls for investigation and punishment of those responsible.

The rights situation also continues to draw international condemnation, and it has motivated an organization of relatives of the disappeared, the Mutual Support Group, to keep up the pressure despite repeated threats and the murders of two of the group's leaders in 1985.

The Mutual Support Group, which Nineth Garcia helped found in June 1984, estimates that 40,000 Guatemalans, most of them Indian peasants, have disappeared since 1976. The group now has about 1,000 members. It says that political disappearances are continuing under the Cerezo government, a charge that Cerezo and top military leaders deny.

After her husband disappeared, Garcia said, she began to search for him in hospitals and morgues. She saw hundreds of bodies, she said, many of them mutilated or showing signs of torture. She went to see Gen. Oscar Humberto Mejia Victores, then president, and begged him to help on behalf of her infant daughter. "I'm sorry for the child," she said Mejia told her.

Garcia spoke after a weekly vigil of the Mutual Support Group in a plaza in front of the National Palace, the seat of Cerezo's government. About 100 people, most of them impoverished Indian women, had gathered to demand justice for their disappeared loved ones.

Like Garcia, they cling to hopes that their loved ones are still alive somewhere, perhaps in secret jails. The military denies that such jails exist, and diplomats and other observers say those who "disappeared" for political reasons before 1986 are probably dead.

Pervading the activities of the Mutual Support Group is a sense of unspeakable tragedy. Their meetings are heartbreaking scenes as the women tell their stories and their listeners weep at the memories of their own losses.

"Certainly, they are in the right morally," said President Cerezo in an interview. "But historically and politically, we must look to the future and not continue looking to the past. What we Guatemalans want is to finish with this matter, because history here has been a history of revenge"

Cerezo said his own Christian Democratic Party has also had its share of "victims of repression," with more than 300 party leaders killed. He has said that he himself survived three assassination attempts under military rule.

"One day we should make a monument to the war, and there the matter should end," Cerezo said. "It's as if the United States had continued the civil war forever." He added, "We have to close the chapter."

In a separate interview, the defense minister, Gen. Hector Gramajo, took a tougher view of the Mutual Support Group, which he charged was a "nihilist" organization that "does not recognize anything positive in Guatemala." He said that many of the 40,000 people who the group says have disappeared could actually be members of guerrilla groups or among refugees abroad.

Cerezo has vacillated on the support group's demand that a special commission be established to investigate the disappearances and punish those responsible. After agreeing, then changing his mind amid military objections, Cerezo two months ago created a commission of four governmental members, two of whom have yet to be named. The commission has not yet convened, although it was supposed to produce a report in 90 days.

Cerezo also has turned down the support group's demand that he work for the repeal of an amnesty that Mejia's outgoing military government proclaimed four days before Cerezo's inauguration in January 1986. The decree in effect bars prosecution of military men for human rights abuses committed between March 1982 and January 1986, covering the tenures of Mejia and his predecessor, Gen. Efrain Rios Montt.

In accordance with Guatemala's new constitution, the congress has formed its own Human Rights Committee, and in November 1986 it passed a law to establish a government human rights "ombudsman." Cerezo tried to veto the law, but failed to do so in time. Now a process of compromise is under way to "reform" the law so that an ombudsman can be named.

Cerezo has said repeatedly that human rights complaints should be taken to the courts, a position also advanced by military leaders. After a number of frustrating experiences with the court system, the Mutual Support Group has rejected this option.

One well-documented case that was taken to the courts concerned the Sept. 9, 1985, disappearance of Luis Fernando de la Roca Elias, a student. Three days after his abduction, his family reported, armed men, several of them with walkie-talkies, brought de la Roca, bound and bleeding, to his home to search it. Afterward, they took him, his mother and one of her granddaughters to the outskirts of the city in two cars. His mother said that the last time she saw her son, he was being beaten in one of the cars. She and her granddaughter were eventually driven home.

Over the next several months, the family filed several habeas corpus writs with the Supreme Court and traced the two cars' license plates to an Army barracks in Guatemala City and the Defense Ministry. In a document dated Feb. 14, 1986, the then-defense minister, Jaime Hernandez Mendez, said that the plates had been "stolen by unknown persons" before the kidnaping and were being used at the time by "elements of the subversive delinquency."

However, further investigation by the family showed that the plates had never been reported stolen and continued to be used by the military. Gen. Hernandez Mendez was accused of involvement in a cover-up. But by July 1986 the courts were no longer responding to the family's submissions and appeared to have dropped the matter.

At present, one of the most controversial aspects of the Guatemalan human rights situation is the question of whether abuses are continuing under the Cerezo administration.

The Mutual Support Group has compiled a list of more than 560 killings and disappearances during Cerezo's first year in office, but it is not clear how many were politically motivated.

In its 1986 human rights report on Guatemala, the U.S. State Department asserts that "killings of civilian noncombatants with possible political implications declined for the fourth year in a row, dropping to 131 in 1986," compared with 280 the year before. It also reports 203 disappearances, of which 79 are cases in which "political motives cannot be ruled out."

According to a Guatemala-based weekly, Central America Report, politically related killings and disappearances averaged more than 33 a month during Cerezo's first 10 months in office. In a report May 15, the weekly said political violence has increased sharply this year. It said March was the bloodiest month in two years, with 107 killings and six kidnapings.

Cerezo insisted that the increased violence this year was of a "common criminal character" and that there were only "three or four cases of a political nature." He added, "The political violence really has ended as an official policy of the government and has decreased almost to zero as a local problem."

A report issued in February by the U.S.-based human rights group Americas Watch and the British Parliamentary Human Rights Group says that politically motivated killings and disappearances continue to occur in Guatemala amid little effort to punish those responsible. It said it believed Cerezo's Christian Democratic government "is not in itself engaged in any plan to commit crimes against any category of opponents," but expressed dismay at its dismissal of these cases as common crimes.

In one case cited by human rights activists, a Christian Democratic Party official, Celso Lopez Jop, was tortured and shot on Dec. 1 near the capital and blamed members of the National Police before dying of his wounds. At least 22 policemen reportedly were relieved of duty and questioned in the case, but no charges have been brought.

On Jan. 25, according to published reports, gunmen in civilian clothes kidnaped Camilo Garcia Luis, a farm worker, in Guatemala City. Two days later his wife, Marta Odilia Raxjal-Sisinit, 22, received a telegram summoning her to a police station, and her mother was abducted from their home. The women's bodies were found buried near their hometown of San Jose Poaquil on Jan. 30. Garcia's whereabouts are still unknown.

In March, a prominent union figure, Jose Luis Lopez, and a student, Jose Calderon Figueroa, were found tortured and shot to death. A union leader said the killings indicated the resurgence of a right-wing death squad, the Secret Anticommunist Army, which operated under the previous military governments and was suspected of having links to security forces.