London (CNN) -- An Iraqi hotel clerk who died in British military custody in 2003 was hooded, handcuffed, held in stress positions in extreme heat and squalor, and died in a state of exhaustion and fear after being beaten, an independent inquiry into the death reported Thursday.
Baha Mousa, 26, was punched and possibly kicked to death while being restrained, retired Judge William Gage found after a yearlong, government-backed inquiry into the abuse of Mousa and nine other men.
Photos of Mousa's battered body accompanied Gage's report, which found the Iraqi had 93 separate external injuries, plus internal ones such as broken ribs.
His father, Col. Daoud Mousa, who was asked to identify the body, said his son was covered in blood and bruises. His nose was broken and part of the skin of his face had been torn away.
It is not possible to determine the identities of everyone involved in killing him, Gage said.
But he said: "All the guards and other officers and men who were aware of what was going on ... must have realized that the treatment of the detainees was wrong. Assaults on them could never be justified."
Gage singled out one guard, Corp. Donald Payne, as having carried out assaults on Mousa and on other men who were detained along with him in September 2003. However, the detainees were also assaulted by other troops "who happened to be passing by the TDF," or temporary detention facility, where the men were held.
Payne devised a practice known as the "choir," the report found -- which involved "punching or kicking each detainee in sequence, causing each to emit a groan or other sign of distress."
Payne was supposed to be supervising the welfare of detainees, Gage observed.
His report acquitted Lt. Col. Jorge Mendonca, the commanding officer of the regiment that held Mousa, but said Mendonca "ought to have known what was going on in that building."
Payne, Mendonca and two other officers "bear heavy responsibility" for the abuse the 10 detainees suffered," Gage's report found.
Payne was charged with manslaughter and war crimes under British law in 2005. He pleaded guilty, served a year in prison and was discharged from the army.
Gage was deeply critical of hooding and the use of stress positions, which he said were "standard practice" in the battalion, and which he said were "wholly unacceptable in any circumstances."
Gage also said the Ministry of Defence did not have any "proper doctrine of interrogation" in place at the time Mousa was killed -- and accused the military of essentially forgetting that the British government had banned techniques, including hooding and sleep deprivation, decades before.
Hooding had been banned orally by British commanders on the ground in Iraq, but transmission of the order was "patchy," Gage said.
Prime Minister David Cameron said an incident such as the killing of Mousa should never happen again, insisting it was "not in anyway typical of the British army."
British Defence Secretary Liam Fox said what happened to Mousa was "deplorable, shocking and shameful."
He said there had been "shocking displays of brutality" and "serious failings of command and discipline" as well as a "lack of moral courage to report abuse."
Ali al-Mousawi, an adviser to Iraqi Prime Minister Nuri al-Maliki, said the Iraqi government believes "there is a fair judicial system in Britain that can assure the rights of Iraqis who were abused by some British troops" and hoped that inquiries "could limit such abuses."
CNN could find little evidence that the average Iraqi was aware of the inquiry, and did not see it mentioned on Iraqi state TV Thursday.
Qassim Bilal, a teacher in Baghdad, said many Iraqis had been tortured, abused and killed by foreign troops since the country was invaded in 2003.
"Why should we care now about one inquiry into the death of one Iraqi?" he asked, as businessman Sami Radhi and student Ali Hussein agreed.
A Twitter user who identified himself as a British Apache helicopter pilot called the report "sickening" but said what happened to Mousa was not representative.
"Luckily it was a small number of idiots. The rest of the army acted professionally during the Iraq war," said Pilot_MikeB, who says he served three tours in Afghanistan. He declined to identify himself further to CNN, saying, "The army can get funny about talking to media."
Gage found that one principal cause, "but not the only cause of the violence," was an unfounded rumor among the troops that the detainees were connected with the murder of a popular officer, Capt. Dai Jones, or of members of the Royal Military Police.
There had been "previous incidents of ill-discipline" in the unit, but there was no "entrenched culture of violence," Gage found.
The British government established an inquiry into the incident in 2008. It got written statements from 388 witnesses, and heard oral evidence from 277 of them.
The inquiry will end up costing about 13 million pounds ($20.7 million), Gage said.
The Ministry of Defence paid 2.83 million pounds (currently $4.5 million) in compensation to Mousa's family and to other men who were detained with him.
The British army apologized at the time "for the appalling treatment that you suffered at the hands of the British army," saying the troops' behavior "made us feel disgusted."
The compensation was paid to Mousa's children and the eight survivors for "pain and suffering" caused by British soldiers, according to a news release from the Iraqis' attorneys.
Mousa had two sons and was caring for two other children at the time he was killed.
CNN's Antonia Mortensen, Jonathan Wald and Mohammed Tawfeeq contributed to this report.