The last time Guatemalan officials told Jennifer Harbury they knew what had happened to her husband, they took her to a remote cemetery and handed her a bucket containing a head they said was his.

A metal cap on one front tooth proved to her that it wasn't.Harbury, a 43-year-old Harvard-trained lawyer, has continued to press the Guatemalan government to reveal the fate of her husband, a Guatemalan guerrilla leader known as as Commander Everardo whom she has not seen since January 1992.

Since Oct. 11, she has been on a hunger strike on the bleak concrete plaza in front of the National Palace, demanding that the government of President Ramiro de Leon Carpio either return her husband's body or, should he still be alive, release him.

Supported by a network of volunteers in Guatemala and efficient publicity in the United States, she has brought so much attention to human rights violations in Guatemala that the country's relations with the United States are being tested.

At first, Harbury had accepted the Guatemalan army's explanation that her husband had been wounded in a fierce firefight on March 12, 1992, and had then shot himself in the head rather than be captured. But in 1993 word came to her that two guerrillas had seen Everardo alive in a secret military prison several months after he had supposedly taken his own life.

In August 1993, there was the exhumation of the wrong body, which only deepened her suspicions.

"I'm 80 percent sure that as of very recently he was alive," Harbury said of her husband during an interview here. "I think there's also a perfectly good chance he's been killed in the last few months."

Her husband's real name is Efrain Bamaca Velasquez, a high-ranking Indian commander of the Guatemalan National Revolutionary Unit, a front of guerrilla organizations opposed to the government.

De Leon Carpio, who handled the case when he was the human rights ombudsman, insists that Harbury's husband is not being held illegally. He says he believes that Everardo was killed in battle more than two years ago and that the only reason his body has not been produced is that the army does not know where it is.

"I can guarantee to Guatemala and to the whole world that no clandestine prisons exist in Guatemala, so there is no possibility that he is being illegally detained," de Leon Carpio said in an interview here on Saturday. He said he was willing to meet directly with Harbury to tell her that. "We have nothing to hide in this case," he said.

The United States has supported efforts by de Leon Carpio to bring democratic change to Guatemala. But officials have expressed disappointment over Guatemala's failure to resolve the case or to remedy its well-documented record of human rights violations, which several rights groups say have increased since de Leon Carpio took office.

Guatemalans are uneasy with the increased attention their country has received because of Harbury, especially because they are nearing the end of complex talks to end a civil war that has been going on for more than 30 years.

De Leon Carpio said Guatemala's ambassador to the United States had been inundated with letters about the case. Pressure is growing to have Congress withdraw aid to Guatemala if the human rights violations do not cease, from police brutality to illegal detentions to summary executions of guerrillas and civilians.

Since she began the hunger strike, Harbury has taken only water and a special solution made of water, salt, sugar, and potassium. She estimates that she has lost about 15 pounds and dropped from a size 8 to a 4 or 6.