GUATEMALA CITY -- (AP) -- A former president has refused to testify in a trial of three former and current soldiers accused of killing a Roman Catholic bishop during his term.

 Alvaro Arzu, president from 1985-2000, told judges Monday he is now legislator of the Central American Parliament, which gives him the right to choose whether to testify.

 His refusal frustrated defense lawyers who had hoped it would help their case in one of the most infamous murder trials in Guatemalan history.

 Bishop Juan Gerardi, head of the Catholic Church's human rights office, was beaten to death with a concrete block on April 26, 1998. The killing came two days after he presented a church report blaming the military for an overwhelming majority of the 200,000 deaths during this country's 36-year civil war.

 Facing murder charges are the former head of military intelligence, retired Col. Disrael Lima; his son and Arzu's bodyguard Byron Lima, an active captain; Jose Obdulio Villanueva, a former member of Arzu's presidential security team; and Gerardi's assistant, the Rev. Mario Orantes.