A judge has threatened to suspend the trial of a US soldier over the abuse at Baghdad's Abu Ghraib jail, urging US prosecutors to speed up their case.
Graner is accusing of punching and stamping on inmates
Col James Pohl told a pre-trial hearing in Germany that delays could derail the court martial of Spc Charles Graner.
Allegedly one of the ringleaders of the abuse, Spc Graner said he feared he would be made a scapegoat, the court was told.
Meanwhile, another of the accused said he would plead guilty to some offences.
Staff Sgt Ivan "Chip" Frederick said in a
statement: "I have accepted responsibility for my actions at Abu Ghraib prison. I will be pleading guilty to certain charges because I have concluded that what I did was a violation of law."
He is accused of maltreating detainees, conspiracy to maltreat detainees,
dereliction of duty and wrongfully committing an indecent
act - but it is not clear to which counts he will plead guilty.
His case is due to come before the court in Mannheim, Germany, in a pre-trial hearing on Tuesday.
But the judge, Col Pohl, said proceedings could be at risk because US government investigators were being slow to conclude their reports.
"I will reconsider whether this case should be dismissed," he warned, after hearing that a single investigator was reviewing
thousands of pages of records on Abu Ghraib.
"The government has to figure out what they want to do with the
prosecution of this case."
Spc Graner is the first of four soldiers to face a preliminary hearing at the US barracks in Mannheim.
He is charged with cruelty and maltreatment of prisoners as well as assault and indecent acts.
Dressed in desert fatigues, he sat impassively beside his lawyers as they requested that the court suppress some of the evidence, including material taken from Spc Graner's computer.
They argued that he was not properly informed of his rights when his room was searched in the middle of the night last January.
Taking the stand later, Spc Graner said he had been taken by surprise by the request to search his room, and spoke of the long hours and stress he was under.
"We worked every day... Several of our platoon had taken fire. Both my roommates had been injured, took blasts. It was one of the most stressful times," said the 35-year-old.
The main investigator told the hearing that procedures had been carried out correctly.
The pre-trial hearing is considering whether the charges against Spc Graner and three other military police reservists are fair and whether they should go before a full trial.
The pre-trial hearing was moved from Iraq to Germany
The hearing was moved to Germany after defence lawyers said it was too dangerous for witnesses and relatives of the accused to travel to Iraq.
Spc Graner's lawyers asked that the full trial also be held in either Germany or the US, but the judge said the request was premature.
Judge Pohl also provisionally rejected the request to suppress evidence from the computer, while stressing it could be reconsidered when it was known what exactly was on the computer.
The judge also heard brief submissions from lawyers for another of the accused, Megan
The scandal erupted in April after images emerged of prison guards abusing and sexually humiliating detainees.