Mr Duelfer, now 51, had been working for a non-partisan
Washington think tank
Woodrow Wilson International Center for Scholars
, where he was researching several projects related to his expertise in defence and military
affairs, as well as
He was last involved directly with Iraq from 1993 to 2000 as deputy executive chairman of the
UN Special Commission on Iraq (Unscom), which was charged with overseeing the disarmament of the Saddam Hussein regime after the first Gulf War.
In that role, he visited Baghdad and other sites in Iraq under the UN mandate to inspect the country's biological, chemical and missile capabilities and verify that they were being brought back within international rules.
'Well suited to task'
Before that, Mr Duelfer served in the US Government as Deputy Assistant Secretary of State for arms control and multilateral defence matters.
From 1990 to 1992 he had been in charge of defence trade issues for the US and was deputy to the Assistant Secretary of State for politico-military affairs.
He received an MSc from the Massachusetts Institute of Technology after a first degree from the University of Connecticut.
David Albright, also a former weapons inspector, said Mr Duelfer had gained respect for his work at Unscom and might be better suited to the search for arms than his predecessor at the Iraq Survey Group,
Mr Albright told the Associated Press news agency that there was a perception that Mr Kay was more of an ideologue, convinced the weapons existed.
"Having Duelfer go in gives me more confidence that they can wrap this up, and we can have some closure. Duelfer has much more experience as an inspector," Mr Albright said.