Those people truely to blame for the degrading treatment of Iraqi prisoners in Baghdad's infamous Abu Ghraib jail remain in the shadows, while such abuses continue unchecked and unseen.

That's the view of American author Tara McKelvey, who sought to uncover the truth behind the 2004 scandal in her book "Monstering: Inside Americas Policy of Secret Interrogations and Torture in the Terror War."

Asked who was really responsible ahead of the trial of the only US military officer charged with tormenting Iraqis at the jail, McKelvey replied: "That's the million dollar question. That's what everyone wants to know."

Lieutenant Colonel Steven Jordan, 51, goes on trial on Monday on charges which include cruelty and mistreatment of detainees, making false statements, obstruction of justice and disobeying orders.

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McKelvey hopes the hearing will provide some answers as to why US soldiers forced their Iraqi prisoners to strip, form naked human pyramids, parade on all fours with leashes chains on their necks, and threatened them with dogs.

"These court-martials have been very useful in the sense that they allow people to ask questions. And they forced people to account for their behavior when they were at the prison," she told AFP.

"They are one of the few venues where things things are out in the open."

So far attempts to the blame the affair on US President George W. Bush, who ordered the invasion of the Iraq in March 2003, his Vice President Dick Cheney or former defense secretary Donald Rumsfeld, the main architects of the war, have come to nothing.

"People try to blame Bush, they blame Cheney, they blame Rumsfeld. But chasing that chain of command is difficult, partly because so much of these documents and the photographs have been withheld from the public," said McKelvey.

She added the "smoking gun" in the scandal could lead to John C. Yoo, who was a lawyer in the office of legal counsel at the Justice Department, and was one of the authors of a key departmental memo.

"In that memo, he defines torture to allow all sorts of abuse and techniques, and that was one of the key points in this entire debate," McKelvey said.

"People say often: torture and abuse have taken place in every war. And it's true, if you look at My Lai or some of the incidents in Vietnam that were horrific.

"But the difference now is that this is codified. There have been allowances made for these things to occur."

The Abu Ghraib scandal first came to light in 2004 when photographs the grinning soldiers had taken of themselves dishing out the abuse to their prisoners shot round the world.

But McKelvey believes the abuse was more widespread than was ever revealed and is probably still continuing in other places and situations.

"It's true you can say the scandal exists because of the photographs, but what you saw on the pictures was really only a fraction of the abuse that was taking place. And certainly not the worst of it," she said.

"There is no question in my mind that the extent was far greater than it was acknowledged at that time. In December 2003, there was something like 12,000 detainees in Iraq," she said.

But there were thousands who were never registered and held in short-term facilities such as schools or police stations, she added.

"Today, polls show that a sizable number of soldiers think that torture is OK in certain conditions, that they won't report abuse if it takes place.

"And I think the sad truth is that these things are still taking place but the difference between now and April-May 2004 is that people aren't taking pictures."