Specialist Armin Cruz, an analyst with the 325th Military Intelligence Battalion, pleaded guilty on Saturday to charges of maltreatment and conspiracy to maltreat detainees.
His guilty plea follows a pre-trial agreement.
Cruz is the eighth person to be indicted in the scandal, which provoked worldwide condemnation when it broke in April.
In a report into the abuse by US army Major-General George Fay issued last month, Cruz was identified as having taken part in the mistreatment of three prisoners at the jail.
He was also mentioned in testimony in another Abu Ghraib case.
A photograph taken in October 2003 shows Cruz and two other intelligence soldiers standing in the background as three prisoners are abused by military police in the foreground.
Senior officials spared
The plea bargain has possibly spared the blushes of more senior military officials who according to at least one soldier at Abu Ghraib - former sergeant with the 372nd Military Police Company, Kenneth Davis - ordered and directed the abuse.
Armin Cruz is the eighth person
to be indicted for prison abuse
The court martial did not touch on the key issue of whether intelligence officers ordered military police to "soften up" prisoners ahead of interrogation, as some have suggested - a link that might indicate the higher chain of command knew about or sanctioned the abuse.
Instead, his lawyer said Cruz took full responsibility for his own actions.
"While his actions which bring him before the court were limited, he takes full responsibility, and in doing so accepts whatever punishment the court deems appropriate for his role in the incident," lawyer Stephen Karns said in a statement.
Major-General George Fay (C)
cited Cruz's actions in a report
In sworn testimony presented in another Abu Ghraib case, Sergeant Samuel Provance, another intelligence soldier, said Cruz "was known to bang on the table, yell, scream, and maybe assaulted detainees during interrogations in the booth".
In his report, Fay said Cruz joined in the prisoner abuse with two military policemen, Sergeant Ivan Frederick and Corporal Charles Graner.
"All three made the detainees act as though they were having sex," the report said.
Cruz also faces a special court martial, rather than a general court martial, a lesser procedure usually presided over by a single military judge rather than a jury panel.
Under a special court martial, the maximum punishment is 12 months' confinement, forfeiture of two-thirds of pay for a year, reduction to the lowest pay grade, and a bad-conduct discharge.
*Photo courtesy of The Washington Post