CAMP BUCCA, Iraq (AP) - The U.S. military on Wednesday closed Camp Bucca, an isolated desert prison that was once its largest lockup in Iraq, as it moves to release thousands of detainees or transfer them to Iraqi custody before the end of the year.
The sprawling facility just north of the Kuwaiti border has held thousands of men over the years, including the most dangerous in U.S. custody - Sunni insurgents, Shiite extremists and al-Qaida in Iraq suspects swept up from battlefields over six years of war.
Iraqi officials say some who have been freed have returned to violence.
"They've been vetted as some of the most dangerous threats not only to Iraq but internationally," said Lt. Col. Kenneth King, the commander of the Bucca detention facility.
On Wednesday, about a dozen of the remaining 180 detainees - some of whom have been held for three years without charge - paced in circles around a fenced-in prison yard, dressed in yellow uniforms and sandals under the watch of a guard tower.
One detainee inside a trailer frantically banged on a metal grill covering his window and shouted in Arabic at a group of visiting reporters, "Open the window!"
By midnight, all were to be transferred to either Camp Taji or Camp Cropper just outside Baghdad, the U.S. military's two remaining detention facilities, while cases are prepared to try to bring them to trial in Iraqi courts. Sixty-five have already been convicted and are awaiting death sentences, said Brig. Gen. David Quantock, the commander in charge of the detention system.
Iraqi officials in the former insurgent heartland around Fallujah have watched with concern as an influx of ex-detainees from Bucca return to homes in places with few jobs, making them easy prey for militant recruiters.
The U.S. military is racing to empty its detention facilities because a security pact that went into effect in January requires them to either transfer detainees to Iraqi custody for prosecution or release them.
The vast majority - 5,600 since January - have been freed due to a lack of evidence that would be admissible in Iraqi courts and the military's unwillingness to compromise intelligence sources by bringing them forward as witnesses. About 1,400 have been handed over to Iraqi custody, and the U.S. military now holds around 8,400 prisoners.
The closure of Bucca is the first major step in shutting down a detention system that was tainted by the Abu Ghraib scandal.
The facility began as a small tent camp for prisoners of war just after the March 2003 invasion, with little more than concertina wire to keep those captured from escaping.
Coalition troops rolling across the Kuwaiti border immediately set about building the camp, and over the next six years it grew into a 40-acre facility filled with row after row of watchtowers, barbed-wire-topped fences and metal trailers or plywood barracks to house detainees.
Named after Ronald Bucca, a former Green Beret and New York City fire marshall killed in the Sept. 11 attacks on the World Trade Center, the camp also houses a forward operating base that will eventually be turned over to Iraqi marines.
The facility was the target of abuse allegations from detainees and human rights groups, which denounced the holding of detainees there for years without charge. It was also the site of riots, including one in January 2005 in which American guards fired on prisoners, killing four detainees and wounding six others.
In May of that year, U.S. authorities thwarted a massive escape attempt when they discovered a 600-foot tunnel leading out of the prison. Dug with makeshift tools fashioned from buckets and tent material 15 feet underground, the escape route reached beyond the compound fence, with an opening hidden beneath a floorboard.
It was uncovered after guards found dirt in latrines and other places. The discovery followed the escape a month earlier of 11 detainees who slipped through a hole in fence at the camp. Ten were eventually recaptured.
After the abuses at Abu Ghraib, the U.S. military implemented a series of reforms, and authorities at Bucca strove to make it a model facility, with closer oversight by commanders and better training for guards. Detainees were segregated based on threat risk, nationality and religious affiliation, and many were enrolled in classes to learn to read and write.
On Wednesday, the camp was eerily empty except for those men remaining in a high-security area known as Compound 16. Vacant units were still decorated with murals painted by detainees. Some showed tropical islands and one depicted a man crouching meekly on the ground.
Many detainees spent their days working at a brick factory on the prison grounds or receiving vocational training. A sign posted at one gate listed basic rights under the Geneva Conventions.
International human rights groups have expressed alarm over the transfer of detainees to an Iraqi judicial system they say falls well short of international standards of fairness. And abuses have occurred in Iraq's prisons, say groups like Human Rights Watch.
"As the Americans dump more detainees in an already overwhelmed Iraqi system, the opportunities for abuse will only grow," said Samer Muscati, a researcher on Iraq at the New York-based rights group.
Camp Taji, north of Baghdad, is scheduled to be turned over to Iraqi control on Jan. 10. Camp Cropper will be the last detention facility handed over, in August of next year.
Cropper, where Saddam Hussein was held before he was executed, houses former members of Saddam's government and other high-value detainees. Among them is Saddam's cousin Ali Hassan al-Majid, known as "Chemical Ali" for the strikes he ordered against Kurds in the 1980s.
Over six years, some 100,000 detainees passed through the system. The highest its population reached at one time was 26,000 in November 2007 after the U.S. troop surge. Of those, Camp Bucca housed the most: 22,000.
Iraqi officials say they have evidence that some released detainees are returning to violence, either in insurgent groups or criminal gangs that have unleashed a frenzy of crime in the Iraqi capital.
A senior Iraqi investigator looking into the truck bombings that killed around 100 people last month outside the foreign and finance ministries in Baghdad said the man who carried out one the attacks was a former detainee at Camp Bucca.