A US Army official said one soldier was convicted of murder in the US military justice system for killing a prisoner in September 2003 at a detention centre in Iraq, and another prisoner was killed at the Abu Ghraib jail near Baghdad in November 2003 by a private contractor who worked as an interrogator for the CIA.
The soldier was reduced in rank to private and thrown out of the service but did not serve any time in jail, the official said. He said the soldier shot and killed the prisoner after the Iraqi inmate had thrown stones at him. The soldier was found to have used excessive force.
The official said the CIA contractor was not in the military, so no legal action was taken because of lack of jurisdiction, but the Army referred the case to the US Justice Department for possible action.
He said a third death among the 25 being investigated was ruled a justifiable homicide: it occurred while a prisoner was attempting to escape.
Details of the inquiries came as the Pentagon investigated the abuse of Iraqi prisoners by US forces at the Abu Ghraib jail. The revelations have inflamed anti-American sentiment, especially in the Arab world.

In the US inquiry, of the other 22 death investigations, 12 prisoners were found to have died either by natural or undetermined causes and a further 10 deaths were still being scrutinised. The Army did not say in which countries the 25 killings occurred but the vast majority were in Iraq.