The US army has appointed a senior general to oversee the inquiry into prisoner abuse at Abu Ghraib prison.
The general will head the inquiry into Abu Ghraib abuses
Four-star Gen Paul Kern will head the probe looking at the role of military intelligence personnel in the scandal at the Baghdad jail.
The investigation was first requested by the commander of US forces in Iraq, Lt Gen Ricardo Sanchez.
But with his own role in the scandal under the spotlight, Gen Sanchez asked to step aside from the inquiry.
Meanwhile, it has emerged that the US military has been secretly holding a suspected terrorist in Iraq on the orders of Defence Secretary Donald Rumsfeld.
The Iraqi man has been held since last November at a high-risk prison near Baghdad, without being listed on any roll or assigned a prisoner number - a "ghost prisoner".
Gen Kern is commander of the US army's Materiel Command, which has the job of providing the equipment and supplies for the military.
He has also served longer as a four-star full general than any other officer currently in the US army apart from the Chief of Staff, General Peter Schoomaker.
BBC Pentagon correspondent Nick Childs says that with a more senior officer now overseeing the probe, Gen Sanchez himself can also be questioned.
The US has insisted that all prisoners in Iraq are treated humanely.
But in March, a report by Maj Gen Antonio Taguba into prisoner abuses at the notorious Abu Ghraib prison criticised the practice of ghost detainees as "deceptive, contrary to army doctrine, and in violation of international law".
Keeping such prisoners violates the Geneva Conventions on treatment of prisoners.
A Pentagon spokesman said the US would end the shadowy status of the prisoner and allow the Red Cross to visit him.
CIA chief George Tenet - who steps down from the post next month - had asked Mr Rumsfeld to have the prisoner secretly detained.
The prisoner, whose identity has not been disclosed, is believed to be a high-ranking member of the radical Iraq-based Ansar al-Islam group. US officials believe he was responsible for attacks on coalition troops in the country.
Afghan jail death
Also on Thursday, a contractor working for the US Central Intelligence Agency was indicted by a federal grand jury on charges stemming from the beating death of a
prisoner in Afghanistan.
North Carolina man David Passaro is the first civilian to face criminal charges related to the
detainee abuse scandal.
Mr Passaro is charged over the 21 June 2003 death of a prisoner in US custody in Asadabad, in the Kunar province of Afghanistan.
The indictment charges Mr Passaro with two counts each of assault and assault with a dangerous weapon - a torch.