Updated

In the first tally of its kind, a U.S. investigative agency says at least 719 people, nearly half of them Americans, were killed working on projects to rebuild Iraq following the U.S. invasion in 2003.

The toll represents an aspect of the Iraq war that is rarely brought to public attention, overshadowed by the much higher number killed in combat as well as the billions of taxpayer dollars squandered on reconstruction.

There is no confirmed total number of Iraq war deaths. The U.S. military lost 4,488 in Iraq, and its allies a little more than 300. The number of Iraq deaths has not been established but is thought to exceed 100,000.

Navy Cmdr. Duane G. Wolfe was among the 719. He was not fighting the insurgency, but it was fighting him.

He was among the army of lawyers, engineers, contractors and others who paid a heavy price trying to put a broken Iraq and its shattered economy back together. Their deaths were recorded among the war's combat fatalities, but until now no one has carved out the "rebuilder" deaths as a subset of the overall casualty list.

Wolfe was killed on May 25, 2009, in a roadside bombing while returning to Baghdad after inspecting a waste water treatment plant under construction near Fallujah in Iraq's western province of Anbar. The $100 million project endured long delays and large cost overruns, and a U.S. federal audit in late 2011 concluded that it probably was not worth the cost. The audit said "many" people died getting it built, but it did not say how many.

The 54-year-old Wolfe, a Navy reservist, was running the Army Corps of Engineers' office in Anbar at the time of his death. Two other U.S. civilians -- Terry Barnich, 56, of the State Department, and Maged Hussein, 43, of the Army Corps -- died in the same bombing.

Wolfe's wife, Cindi, said in a telephone interview last week that he knew the dangers of working in Iraq but made a point of not talking about security or any close calls that he might have had.

"He was careful not to worry us with information like that," she said.

The actual number of people killed doing reconstruction work is probably much higher than 719 but cannot be reliably determined, the Office of the Special Inspector General for Iraq Reconstruction said in releasing its estimate Friday. The U.S. government has no central database for this category of war casualties, and even within the U.S. military, the records on hundreds of troop deaths are too imprecise to categorize, the report said.

"We know our number is understated," Glenn D. Furbish, the deputy inspector general for Iraq reconstruction, said in an interview.

Sen. Susan Collins, a Republican, called the report a "reminder that attempting to build roads, schools and other infrastructure in the middle of a war zone not only carries with it an increased frequency of fraud and waste, but also a devastating price in human life."

The 719 include U.S. government civilians, private contractors, military members, Iraqi civilian workers and third-country nationals. They were trainers, inspectors, auditors, advisers, interpreters and others whose mission was directly tied to the largely ad hoc reconstruction effort that began early in the war. They helped restore Iraq's dilapidated electrical grid, improve its oil infrastructure, develop a justice system, modernize a banking system, set up town councils and reopen hospitals, training centers and schools.

They also helped recruit and train Iraqi police, and they advised the Iraqi army. These trainers and advisers, mostly U.S. military members,- were considered part of the reconstruction effort if their mission was development of the Iraqi security forces, which had been disbanded by the U.S. occupation authorities in May 2003.

None of the 719 was named in the report, but some of the Americans have been recognized publicly by the government.

Among U.S. adviser casualties was Master Sgt. Anthony Davis, 43, who was shot to death Nov. 25, 2008, by an Iraqi soldier while delivering relief supplies. The shooter was in the battalion that Davis was advising as part of a military transition team. Davis's team also assessed schools' needs and planned renovations and organized deliveries.

The special inspector general's report did not calculate how many U.S. troops were victims of insider attacks, a problem that has drawn wider attention in Afghanistan in recent months.

Insurgent attacks posed one of the biggest, and least anticipated, obstacles to the reconstruction effort in Iraq, which cost American taxpayers about $62 billion. Sabotage, waste and fraud took their own toll. The human cost, however, was far greater than foreseen when the invaders swiftly toppled Saddam Hussein.

"A completely exact calculation is not possible," the report said, One reason is that the U.S. military's reports on 1,009 casualties were so thin on detail that the type of mission could not be determined. As a result, the investigators could not count any of those in the reconstruction death total.

The 719 killed include 318 Americans, of which 264 were military members and 54 were civilians. The total also includes an estimated 271 Iraqi civilians and 111 third-country nationals, as well as 19 people of unknown nationality. The figures were compiled by combing through a range of documents, including classified data on roadside bomb attacks, according to Craig A. Collier, who directed the project as a senior adviser to the special inspector general for Iraq reconstruction.

Although the 719 killed represent a relatively small percentage of total war deaths, it far exceeds the 172 U.S. and coalition troops killed in the initial invasion, before President George W. Bush's declaration on May 1, 2003, that combat operations had ended. At that point it was mistakenly thought that the war was largely over.

Another of the 719 was Paul Converse, who died March 24, 2008 of wounds suffered in a rocket attack on the heavily protected International Zone in Baghdad that housed the U.S. Embassy and some Iraqi government offices.

Converse, 56, was an auditor with the same office that did the death tally released Friday.