An American soldier convicted of abusing prisoners in an Iraqi jail has been sentenced to one year in prison.
Sivits is the first soldier convicted in the scandal
Jeremy Sivits admitted abusing inmates and photographing them in humiliating poses at Baghdad's Abu Ghraib jail.
Sivits, the first person to be found guilty over the scandal, was also demoted and discharged from service.
Fighting back tears, Sivits testified that colleagues at the prison told him senior officials had ordered the abuse to get the prisoners to talk.
Earlier, three other soldiers charged with mistreating Iraqi detainees declined to enter pleas at their pre-trial hearing.
Before he was sentenced, an emotional Sivits told the court he felt remorse for his actions.
"I'd like to apologise to the Iraqi people and those detainees," Sivits said, breaking down in tears.
"I should have protected those detainees, not taken the photos."
Recounting the abuse against the prisoners at Abu Ghraib, Sivits told the court that on 8 November 2003, Staff Sgt Ivan Frederick told him to go to where the prisoners were gathered.
"I heard Cpl [Charles] Graner yelling in Arabic at the detainees," he said.
"I saw one of the detainees lying on the floor. They were laying there on the floor, sandbags over their heads."
He said Sgt Javal Davis and another soldier, Pte Lynndie England, were "stamping on their toes and hands".
Sivits said Cpl Graner complained he hurt his hand when he punched a prisoner in the head.
He said his colleagues told him they were ordered to abuse the prisoners.
"They said that they were told by military intelligence for them to keep doing what they were doing to the inmates because it was working, they were talking."
The former mechanic from Pennsylvania pleaded guilty to conspiracy to maltreat detainees, maltreatment of detainees and dereliction of duty.
The BBC's Dumeetha Luthra in Baghdad says lawyers for some of the other soldiers have already dismissed Sivits' accusations as fabrication.
Most of the other soldiers maintain they were following orders, while Sivits says these were all individual actions, a stance the administration is keen to push, our correspondent adds.
ABU GHRAIB: THE ACCUSED
Spc Jeremy Sivits: First to be tried, pleaded guilty
Sgt Javal Davis: Charges include cruelty and maltreating prisoners
Sgt Ivan Frederick: Charges include assaulting prisoners and committing indecent acts
Spc Charles Graner: Charges include maltreating and assaulting prisoners
Pte Lynndie England: Charges not announced
Spc Sabrina Harman: Charges not announced
Spc Megan Ambuhl: Charges not announced
Earlier on Wednesday, Staff Sgt Frederick, Sgt Davis and Spc Graner, who are also implicated in the abuse scandal, appeared in court.
They face more serious charges than Sivits, including physical assaults on prisoners.
They deferred entering pleas and were ordered to appear in court again on 21 June.
Unlike Sivits, who maintains senior commanders knew nothing about the abuse, the others are expected to contend that they were following orders as a means of "softening up" detainees before interrogation.
In Washington, three senior US commanders in Iraq have appearing before a Senate committee on the abuse scandal.
Central Command chief General John Abizaid, the commander of US forces in Iraq Lieutenant General Ricardo Sanchez, and Iraq prisons chief Major General Geoffrey Miller were questioned.
During the hearing, the committee chairman, Senator John Warner, revealed that the defence department had located another disc of pictures relating to the abuse of Iraqi pictures.
Gen Abizaid and Gen Sanchez admitted there were problems, such as overcrowding, in Iraqi prisons, but insisted there was no widespread abuse of prisoners.
"I don't believe that the culture of abuse existed in my command," Gen Abizaid said.
'Tantamount to torture'
The US is keen to show these were isolated incidents and will be dealt with swiftly, firmly and openly.
But the International Committee of the Red Cross has cast fresh doubt on the treatment of detainees.
ICRC director of operations Pierre Krahenbuhl told the BBC Panorama programme procedures at Abu Ghraib jail were still a cause of concern, despite being highlighted in a confidential February report.
The US has said that the ICRC made its concerns known directly to the US command in Baghdad last autumn and that some corrective actions were taken.
Mr Krahenbuhl said some aspects of treatment and conditions identified in a secret report produced in February were "tantamount to torture".