By Benjamin Reeves McClatchy Foreign Staff (MCT) GUATEMALA CITY _ Representatives of Guatemala's indigenous Ixil Maya have filed a petition with the Inter-American Commission for Human Rights in Washington accusing the Guatemalan government of failing in its legal obligation to investigate and prosecute genocide. The petition, which was filed Wednesday, was in response to an order by one of Guatemala's highest courts requiring a lower court to consider amnesty for former President Efraim Rios Montt, whose forces conducted a bloody campaign against Guatemalan indigenous groups in the early 1980s. "We presented a petition ... because we want Guatemala to be held accountable for the crimes committed against the Ixil people," said Marcia Aguiluz of the Center for Justice and International Law. "We want the Inter-American system to give a judgment that Guatemala must investigate and judge these people." Prosecuting Rios Montt for what took place during his rule has been a challenge from the beginning. The lead Guatemalan prosecutor on the case, Edgar Perez, has received multiple death threats. Since August 2010 he has traveled with nearly constant protection provided by the human rights group Peace Brigades International, which said it has thwarted a number of attempts on his life, including an attempt to tamper with the brakes on his car. Rios Montt, 87, was convicted in May of genocide against the Ixil people. Over a two-year period in the early 1980s, as many as 95 percent of Ixil villages were razed and several thousand people, roughly 5.5 percent of the Ixil population, were killed. But Guatemala's Constitutional Court overturned the conviction 10 days later and ordered a retrial, which was expected in early 2014. In October, the Constitutional Court ordered the lower court to reconsider whether Rios Montt was eligible for a 1986 amnesty, even though a subsequent Guatemalan law and international law says such amnesties did not apply to crimes against humanity. A final blow came Tuesday, when the Constitutional Court informed plaintiffs in the genocide case that there could be no retrial until early 2015 because the court's calendar is full for 2014. Advocates of trying Rios Montt expressed concern that he might die before further legal action takes place. "There are, of course, concerns about unjustified delays," said Roxanna Altholz, associate director of the International Human Rights Law Clinic at the University of California, Berkeley, School of Law. "Rios Montt is an older man, and these crimes occurred over 30 years ago."