A prisoner who was a witness at the trial of 27 police officers for torturing inmates in a prison in southern Argentina was murdered a month before he was to be included in the program of temporary releases, a non-governmental organization investigating the case told Efe on Monday.

Cristian Ibazeta was attacked and stabbed about 20 times on May 21 at Prison No. 11 in Neuquen province and died on the 25th from the injuries he sustained.

According to police, the prisoner's injuries were caused by other prisoners, a hypothesis that the Zainuco human rights organization called into question.

"He had never suffered injuries or had problems with any companion in the prison," said Gladys Rodriguez, the president of Zainuco, an organization that in 2010 was prominent in the trial of 27 police officers from the same prison accused of torture. Ibazeta testified at the trial and six officers were found guilty.

The torture was carried out in 2004 after inmates took over three wings of the prison to protest the bad treatment they and visitors had suffered, including Ibazeta's mother whom police "forced to strip naked" during a visit, sources with the NGO said.

Zainuco said that the judiciary would be asked to investigate the death of Ibazeta, who in addition to testifying in the trial of the police officers had filed seven complaints for mistreatment by prison authorities, the reason why he had been sent to several prisons around the country.

"For us, it's not believable that this was a problem among prisoners. For us, there is clear responsibility of the state, given that Cristian Ibazeta was not just any inmate. He was in confrontation with the police and not with his cellmates," Rodriguez said. EFE