Everhart worked at the American University in Cairo, where he was associate dean of the Business School and a finance professor. Before joining AUC, he worked extensively with the World Bank and the Overseas Private Investment Corporation, a US government agency designed to help businesses break into developing markets.

He also wrote articles on topics like international aid, corruption and financial markets.

Officials at Georgia State University said Everhart listed San Antonio, Texas, as his hometown on his registration paperwork. Everhart got both his master's and doctorate in economics at Georgia State in Atlanta.

Mary Beth Walker, dean of the School of Policy Studies, said Everhart met his wife, Stephanie, while in graduate school there. She described him as a "hard worker" with a good sense of humor.

Walker said Everhart had contact with Georgia State faculty members in the last two weeks about his work in Iraq and said he was planning to move to Vietnam soon to work at a university there.

The State Department gave no information about how he was killed, but an Iraqi police official said the American contractors were visiting a satellite office of Mustansiriyah University in eastern Baghdad when they were hit by a roadside bomb.

It was not known whether the assailants knew Americans were in the convoy or not. It is extremely rare for an American working so closely with the State Department to be killed.

Shiite militias who operate in the nearby neighborhood of Sadr City have stepped up attacks against the US military in recent months and threatened violence against other American targets. Nine American soldiers have been killed in Iraq so far this month, one of the highest death tolls in two years.

The US military has also accused Shiite militias of lobbing mortars and rockets at the US Embassy in the Green Zone.

Shiite militias are trying to claim they are driving the US military from Iraq and make the US think twice before agreeing to have US troops stay in the country past the December 31 date by which they're slated to go home.

The attack against Everhart and the other contractors could have serious repercussions for the US Embassy in Baghdad and the ability to conduct operations in the country. Already, US Embassy staff and contractors working with agencies such as USAID generally travel in armored vehicles with guards and sometimes with US military assistance.

Earlier this week, a convoy carrying French Embassy staff was targeted by a roadside bomb in the Karradah neighborhood. No one was killed in that incident.