Myrna Mack knew the death squads were after her. The 40-year-old anthropologist who had documented army atrocities against Indians asked neighbors to watch for strangers outside her home, began varying her travel habits and told a priest she feared for her life.
They got her anyway. On the afternoon of Sept. 11, 1990, attackers stabbed Mack 27 times outside her downtown office. She died in a puddle of blood.
Noel Beteta Alvarez, a member of Guatemala's presidential guard, was eventually convicted of the murder and is serving 25 years in prison. But activists complained those behind the killing had gone unpunished, and it wasn't until last week that a retired general who once headed the guard and two colonels in the unit went on trial for allegedly giving the orders.
The trial is again casting the spotlight on the presidential guard, an elite force set up to protect the president but that allegedly grew into a squad of spies and assassins responsible for some of Guatemala's most high-profile killings. Government leaders have promised for years to disband the guard, but none has.
Prosecutors say corrupt army generals and presidents long used the guard to silence those who tried to investigate their secrets, particularly abuses committed by the army during the 1960-96 civil war.
Last year, José Obdulio Villanueva, a former member of the presidential guard, and guard member Capt. Byron Lima were convicted of murdering Roman Catholic Bishop Juan Gerardi in 1998. Gerardi, the head of the church's human rights office, had just released a report accusing the military of atrocities.
The presidential guard was also implicated in a fatal machine-gun attack on journalist Humberto González in 1990 and in the 1996 disappearance of guerrilla leader Juan José Cabrera.
Prosecutors say Mack became a target after angering the military with a groundbreaking 1990 report that accused state anti-insurgency campaigns of destroying hundreds of Mayan communities.
Three days before the trial began last week, assailants fired machine guns at the home of Roberto Romero, head lawyer for a human rights group founded by Mack's sister. Police assigned to protect Romero's home disappeared moments before the attack, and activists suspect official involvement.
''There are a lot of ex-military people who don't want to see justice in this case,'' said Adriana Beltrán, a Guatemalan specialist for the Washington Office on Latin America, a human rights monitoring group.
Prosecutors say the presidential guard converted itself into a paramilitary killing machine during the civil war, using its intelligence operation to spy on thousands of suspected rebel sympathizers. They say its anti-kidnapping force tortured leftists and its agents became assassins, settling scores for presidents or their friends in the army.
''In a country full of dangerous groups, [the guard] was probably the most frightening for social organizations and ordinary citizens. They could target anyone,'' said Julián Camarero at the U.N. Mission to Guatemala. ``In many ways the presidential guard was much more powerful than the military.''
Peace accords ended the war in December 1996 and recommended that the unit be disbanded. In 1999, then-President Alvaro Arzú pledged to get rid of the guard but never followed through.
President Alfonso Portillo announced during his inaugural address in January 2000 that he would do away with the group, and Washington sent $2 million to help the government train a civilian force to replace it. But the unit remained in place.
Last month, the government again announced it would dismantle the guard, this time with a deadline of next July.
Given the history, ''it was hard to believe'' the latest promise, Beltrán said.
Calls to the presidential guard's fortress-like headquarters weren't returned, and a written request for an interview went unanswered.