Duelfer replaces David Kay, who has led the search since Saddam's fall. Kay had told associates last month that he was considering leaving the post, according to The New York Times.
Duelfer served from 1993 to 2000 as the deputy executive chairman of the U.N. Special Commission on Iraq, making him the No. 2 U.N. weapons inspector there at the time, according to the Associated Press. The commission was in charge of eliminating weapons of mass destruction and ensuring Saddam did not resume their production after the 1991 Gulf War.
As a negotiator for UNSCOM, Duelfer frequently visited Baghdad and has dealt with many of the Iraqi arms dealers who are now in U.S. custody, Reuters reported.
Duelfer has expressed doubt that any weapons of mass destruction will be found in Iraq because of the extensive interviews with Iraqi scientists and the incentives the United States has offered for information.
Nonetheless, the potential was there for Saddam to develop the weapons, Duelfer said in a Jan. 9 NewsHour interview: "Now maybe [Saddam] didn't have weapons today, but I think there is certainly evidence of his intention to develop those weapons once the attention of the U.N. and the international community changed to other matters."
Duelfer will take over for Kay as head of the Iraq Survey Group, a coalition of military and civilian personnel looking for illicit weapons in Iraq.
Kay's last public report, issued in October, said the team found no illicit weapons in Iraq, but did find evidence of plans to reconstitute its nuclear, biological and chemical programs.
"What we have found is a substantial body of evidence that reports that the Iraqis had an intention to continue weapons production at some point in the future," Kay said in an Oct. 2 NewsHour interview. "We've also found undeclared activities in the chemical and biological and missile area that were never declared to the U.N. and not discovered during inspections. So we have a lot of activity and we simply don't know whether that points to weapons or does not."
The Bush administration said the report supported its stance that Saddam was trying to deceive the international community and posed a threat to the world. The development of weapons of mass destruction was one of the main reasons the administration gave for invading the country last year.
Democratic lawmakers, however, focused on the fact that Kay's team had not found any illicit weapons and said the report showed Saddam did not pose an immediate threat.