Myrna Elizabeth Mack Chang, a Guatemalan anthropologist investigating military atrocities in rural indigenous communities, was stabbed to death 27 times outside her office on September 11, 1990. According to Amnesty International, her murder occurred after the publication of Mack’s ground-breaking study which concluded the Guatemalan government counter-insurgency policies had caused the internal displacement of Guatemala’s Mayan indigenous people and their subsequent suffering.

Helen Mack, sister to Myrna, formed the Myrna Mack Foundation and has spent over a decade campaigning for support in the international community to push the Guatemalan government to take action for this atrocious crime as the mastermind that ordered the assassination. The Mack Foundation also filed a petition with the Inter-American Commission of Human Rights alleging the Guatemalan government violated a number of articles in the American Convention on Human Rights in this case.

The investigation, prosecution and trials are a testament to the persistence of Helen Mack.

During the investigation, policemen and numerous witnesses were forced into temporary and permanent exile, while those that have remained in Guatemala have been the subject of threats and harassment. Two police investigators produced a report in which they concluded Myrna Mack had been murdered for political reasons and named a member of the military as one of the suspects.

In 1993, Noel Beteta, an army sergeant who worked in the Security Division of the Presidential Guard (Estado Mayor Presidencial or EMP) was convicted of the murder of Myrna Mack and sentenced to 25 years. Beteta subsequently revealed that he had been acting on orders from higher levels in the military.

Retired General Edgar Augusto Godoy Gaitan, Colonel Juan Guillermo Oliva Carrera and Colonel Juan Valencia Osorio were finally indicted. These three officers had been Beteta’s superiors within the Presidential Guard. The process of bringing them to trial was subject to serious delays due to ongoing threats, lack of political will, numerous motions by the defendants, and possible impediments to the independence of the judicial bodies hearing the motions.

Lawyers, judges and witnesses were subjected to serious threats to their safety as a result of their involvement in the investigation and trial. One of the police investigators who concluded that Myrna Mack had been murdered for political reasons was himself murdered in 1995 and his colleague fled the country. The Secretariat of Strategic Analysis threatened Carlos Coronado, then the prosecutor in charge of the case, that he himself was the subject of an investigation. The President of the Guatemalan Constitutional Court was assassinated in 1994 just as he was about to rule on an appeal regarding the case. Throughout the years, Helen Mack was frequently under threat.

Concerns for the safety of the jurists and witnesses involved in the prosecution were heightened by Amnesty International’s report that human rights in Guatemala have deteriorated. The assessment was echoed in reports from The International Commission of Jurists that jurists in Guatemala face an escalating number of attacks including murder (at least 13 between March 2000 and March 2001), robbery, anonymous telephone threats, surveillance of workplaces and residences, and loss of reputation.

The trial of retired General Edgar Augusto Godoy Gaitan, Colonel Juan Guillermo Oliva Carrera and Colonel Juan Valencia Osorio finally commenced on September 3, 2002. In addition to the State prosecutors, the Myrna Mack Foundation itself participated in the prosecution of the case on behalf of the victim, a role permitted under Guatemalan law. Shortly before the trial began, on August 23, 2002, Roberto Romero, one of the lawyers prosecuting the case on behalf of the Myrna Mack Foundation, received death threats. Shortly thereafter, a group of unknown individuals fired at Mr. Romero’s home. [AI Index: 34/051/2002]. During the trial, police protection was provided to Mr. Romero and the other personnel of the Mack Foundation involved in the proceedings. Nonetheless, Mr. Romero’s family were subjected to further telephone threats and other intimidating actions. A member of the Mack Foundation staff was also subjected to an incident of intimidation during the trial. Before the trial ended, Mr. Romero’s immediate family left the country for their own safety.

Vancouver lawyer Brenda Wemp was in Guatemala from September 10 to 25th 2002 on behalf of LRWC to observe the trial of these three former high ranking military officials. This trial was precedent setting in the struggle within Guatemala to end impunity, in that it is the first time that high-level military officers were brought to trial for planning and ordering a murder.

LRWC was asked to attend the trial, together with other international observers, to signal concern for the safety and independence of the jurists, interveners, and witnesses involved. Threats and intimidating incidents directed at the lawyers and legal team representing Helen Mack continued during the trial in September, despite the provision of police protection by the Guatemalan government, following an order of the Inter-American Court for Human Rights.

The prosecution’s case was based on the argument that the crime was a politically motivated, institutional crime, carried out by an officer of the Presidential Guard using material resources of that institution. The higher officers in the chain of command must, therefore, have planned and ordered the murder. Much of the evidence consisted in expert testimony and documents with respect to the structure and function of the Presidential Guard.

The only evidence directly implicating the accused was a series of tape recordings and one video recording in which the material author of the crime, Noel de Beteta, confessed and stated that he had carried out the murder on the direct order of the head of the Security Division. These tapes were recorded in prison after Beteta was convicted, by a fellow prisoner, Jorge Lemus. Lemus testified at the trial, as did Beteta. However, Beteta totally recanted his earlier statements, alleging he was on drugs at the time the tapes were made, and that the drugs were purchased with money furnished by Helen Mack.

On October 3, 2002, the three judge panel of the Supreme Court of Guatemala convicted Colonel Juan Valencia Osorio, a former top official of the notorious Presidential Security Unit (EMP) for ordering the September 11, 1990 murder of Myrna Mack and sentenced him to 30 years imprisonment.

Valencia’s superior officer, General Edgar Augusto Godoy Gaitan and Noel Beteta’s immediate superior officer, Colonel Juan Guillermo Oliva Carrera, were acquitted on the grounds that there was insufficient evidence establishing their direct involvement with the murder. Valencia’s conviction was based in part on a video taped statement by Beteta that he had murdered Mack on the orders of Valencia. Beteta gave evidence at trial repudiating the statement and saying that he had made it while high on drugs and in prison.

The Myrna Mack trial has been described as “an important step in lifting the veil of official secrecy and impunity regarding the violence that terrorized the nation from 1960 until 1996 and resulted in more than 200,000 deaths”.

Valencia’s conviction represents the first time that a high ranking military official has been tried and convicted for a crime committed during Guatemala’s 36 year internal conflict. Only once before had a military officer been convicted for a political crime in Guatemala.

Valencia’s conviction is also the first time in Guatemala that a military officer has been convicted for ordering a crime carried out by a subordinate.


In May 2003, the Fourth Appeals Court of Guatemala reversed the conviction of Colonel Juan Valencia Osorio and upheld the acquittal of the other two officers. The decision with respect to Valencia Osorio was appealed to the Supreme Court of Guatemala, and in January 2004, the Supreme Court reinstated his conviction.

That decision brought an end to domestic criminal proceedings in the Mack case. The conviction of Valencia Osorio represents the first time a high ranking military officer has been convicted of a human rights violation committed during the country’s civil war.

In addition to the domestic proceedings, Helen Mack had brought a parallel case against Guatemala to the Inter American Commission on Human Rights for violations of Myrna’s right to life and the rights of her family to humane treatment and judicial protection. The Commission referred the case to the Inter-American Court of Human Rights (IACHR) in 2001. Oral arguments were heard in February 2003 and in November 2003, the Inter-American Court of Human Rights (IACHR) ruled that Guatemala was responsible for the murder of Myrna Mack and the subsequent denial of justice in the case. The IACHR also found that the commanding officers in the EMP had ordered and carried out the murder, and directed Guatemala to make reparations, including monetary damages in the highest amount ever awarded by the Court.

RECOMMENDED READING: See information about this case on the website of Human Rights First (formerly the Lawyers’ Committee for Human Rights, at .


  • Preparation of fact summary relevant to security and independence issues.
  • Letters to Guatemala government officials and departments.
  • Attendance at trial – LRWC sent Vancouver lawyer Brenda Wemp to attend the trial in September 2002, as a gesture of moral support, and to send a message that Canadian lawyers are aware of the proceedings and concerned about the safety of those involved. While in Guatemala, Ms. Wemp visited the Myrna Mack Foundation and met with staff, expressing the concern of LRWC for their safety. In the course of the trial, she also met with both State prosecutors as well as with the Prosecutors for the Myrna Mack Foundation, and with Helen Mack. Ms. Wemp was also introduced to the Attorney General of Guatemala, who attended the trial in the company of James Lambert, Canadian Ambassador to Guatemala.

Update April 2005