Guatemala City ( CNN ) -- When former Guatemalan dictator Efrain Rios Montt was convicted of genocide and sentenced to 80 years in prison this month , it was not expected to be the end of story . READ MORE : Guatemala 's Rios Montt guilty of genocide . Observers knew that an appeal was coming , but it was a separate action -- a ruling by Guatemala 's Constitutional Court -- that provided the latest twist in the case . The Constitutional Court on Monday overturned Rios Montt 's conviction and sentence , and ordered the proceedings to return to the trial phase . The ruling does not annul the entire trial , but everything that happened after April 19 , notably the closing arguments and conviction . The overturning of the conviction is related to a number of procedural complaints filed by the defense . The defense had argued that Rios Montt 's rights had been violated when his attorney was expelled early in the trial , and that the head judge should have recused herself . The Constitutional Court decided that the trial should have been suspended while these appeals were in place , instead of pushing forward a conclusion . Rios Montt , 86 , had been found guilty of the genocide of more than 1,700 indigenous Ixil Mayans during his 1982-83 rule . The trial marked the first time a head of state was tried for genocide by his country 's own judicial system . Dozens of Ixil Mayans took the stand during the trial to recount atrocities committed by the army . The witnesses told the judges about brutal killings , rapes and the razing of villages . The Constitutional Court 's ruling allows their testimony to stand . The trial 's original outcome was seen as a precedent for future charges against military officials accused of atrocities during Guatemala 's 36-year civil war . The war did not end until 1996 , leaving more than 200,000 people dead and 1 million as refugees . Rios Montt said during the trial that he never ordered the killings of the Ixil . `` We have reached the conclusion that there is still hope for justice , which is the Constitutional Court , '' Rios Montt attorney Mario Antonio Rossell said . `` This is a historic resolution . '' Human rights groups say they will appeal the decision . `` What has happened is that in this country , the laws have been applied arbitrarily , '' said Mario Polanco , director of a Guatemalan human rights group . `` They have served the interests of those in power , and when it is one of the representatives of those in power who is on trial , they will resort to any means , and that is what we are seeing . I think there has been an abuse in the interpretation of the law . '' READ MORE : Rios Montt rejects genocide charges as history-making trial nears end . READ MORE : Guatemala confronts a dark chapter . CNN 's Mariano Castillo reported and wrote the story in Atlanta . Journalist Miguel Salay reported from Guatemala City .
Guatemala 's Constitutional Court overturned the conviction of Efrain Rios Montt . Rios Montt was convicted of genocide and sentenced to 80 years . The court said the proceedings must return to the trial phase . Human rights groups say they will appeal .