The Jara family's lawyer, Nelson Caucoto, also complained about this Wednesday, saying that Chile's military still denies having any information about which officers were assigned to the stadium in September 1973.
But Caucoto added that many former prisoners and army conscripts did share their memories, including a former draftee named Jose Paredes, who was charged years ago with Jara's murder even though he denied firing the machine gun into the singer's body.
Paredes told The Associated Press in 2009 that he gave information on officers, and in the end the judge charged eight former lieutenants. Barrientos and Hugo Sanchez Marmonti are accused of murdering Jara. Charged as accomplices are Roberto Souper Onfray, Raul Jofre Gonzalez, Edwin Dimter Bianchi, Nelson Haase Mazzei, Ernesto Bethke Wulf and Jorge Eduardo Smith Gumucio.
Four of the six defendants living in Chile turned themselves in Wednesday, and were being held at a special prison for military personnel charged as human rights violators. When Marmonti was taken before the judge Wednesday, he firmly said "No" when reporters shouted questions asking if he was guilty.
Barrientos and Dimter have both been accused by human rights activists over the years of being "The Prince," a sadistic blond-haired officer who survivors said walked around with a whip in the stadium, taunting and torturing prisoners. Both men have denied this, and the judge has not released any information on that accusation.
Associated Press writers Michael Warren in Buenos Aires and Eva Vergara in Santiago contributed to this report.