Hassan is not the only Iraqi scientist to say he wasn't lying. 

Amer Al Sa'adi, the scientific adviser to Saddam Hussein, has turned himself in to U.S. authorities. Yet he also is sticking to his original assertion that Iraq had no weapons of mass destruction programs. 

The U.S.-trained former head of Iraq's biological warfare program, Nassir Hindawi, says fear of retribution from remnants of Saddam Hussein's Baath Party stops him from surrendering to U.S. troops searching for him, but CNN found him and interviewed him. 

"In every street there are members of the Baath Socialist Party that are probably hoping and dreaming of getting power again," he said. "They have weapons and arms ... and so nobody knows how the country is going to be in the future." 

Hindawi admits he lied to inspectors until his cover was blown in the mid-1990s. Since then, however, he says he has been telling the truth. 

"As far as biological weapons are concerned, there is no need to search for that because the toxins were crude proteins," he said. 
 

According to U.N. inspectors, Iraq had several thousand scientists and engineers like Hindawi who were involved in Iraq's WMD programs. Not knowing where all of them are and what they are doing is raising concerns about post-war efforts to control what may be left of Iraq's weapons programs.  "Any weapons of mass destruction or the equipment to make them is unprotected, and given the looting, you have to assume that some of it has been taken away," said David Albright, a former U.N. weapons inspector.  "The scientists have to worry about their future, and they may opt to leave Iraq looking for a better future ... there may be some scientists who have a deep grudge against the United States," Albright said. "Who knows [if they] are going to try to find some way to get revenge?"

U.N. inspectors visit the Al Dora Foot and  Mouth Disease Institute in Iraq.

"If no WMD are found, then the fundamental justification for this war is not there, and there's going to have to be some real answers why we went to war and how did the U.S. make such a huge mistake about the WMD programs in Iraq," he said. 

Questions have arisen about the quality of the intelligence cited by Great Britain and the United States to make the case for an aggressive U.N. inspection program. 

In October 2002, President Bush spoke in Cincinnati, Ohio, and displayed a satellite image of a facility called Al Furat. He said the picture revealed the rebuilding of a past nuclear facility -- which bolstered his contention that Iraq was reconstituting its nuclear weapons program. 

In response, Iraqi officials rushed hundreds of journalists to Al Furat to show Iraq had nothing to hide. When U.N. inspectors returned to the country, they visited Al Furat on their third day and journalists were allowed back. 

"We don't have anything as far as this site is concerned. We don't have anything to hide," Hassan told reporters taking the tour. 

Inspectors returned several more times to Al Furat. 
 

Then on March 7, less than two weeks before the war began, top inspector Mohamed ElBaradei, director-general of the International Atomic Energy Agency, said IAEA inspectors could not verify that Iraq had a nuclear weapons program.  "There is no indication of resumed nuclear activities in those buildings that were identified through the use of satellite imagery as being reconstructed or newly erected since 1998, nor any indication of nuclear-related prohibited activities at any inspected sites," El Baradei told the U.N. Security Council.  Like many places in Iraq, Al Furat was looted after the war. Even door frames were removed. The junked equipment left at the ravaged site seems to support the deposed Iraqi regime's claims that Al Furat was nothing more than a radio frequency testing and repair facility.

U.N. inspectors came back many times to the former Al Furat nuclear facility but found nothing  but junked radio equipment.

The new team of inspectors came to Al Dora Institute on the second day of work in November, 2002, to follow up on suspicions that bio-weapons work had resumed. 

Inspectors found two mixers missing but those were quickly tracked down. Iraqis denied WMD work had started up again. 

Plant Director Montasar Al Ani was eager to show journalists how the site was disabled by U.N. inspectors back in 1996. He repeated his assertion that he is unaware of a weapons program after 1994. 

"I am not responsible for that," he said, adding that he had not been working there before 1994. 

Despite more visits by inspectors to this and other sites flagged by the United States and Great Britain, the U.N. failed to substantiate any WMD programs. 

Privately, inspectors told reporters they were frustrated by the bad intelligence information provided by the U.S. government. Chief U.N. weapons inspector Hans Blix hinted as much in a February 14 briefing to the U.N. Security Council. 

"We must recognize that there are limitations [to intelligence] and that misinterpretations can occur," Blix said. 

Since the toppling of Saddam's regime, more has been learned about intelligence gathering in Iraq. 

The Iraqi National Congress revealed that Mohammad Mohsen Zubaidi -- the self- appointed mayor of Baghdad now in U.S. custody, accused by Iraqis of receiving looted funds -- was one of the INC's top intelligence-gathering officials in Iraq. The INC has close ties to the Pentagon. 

"The problem isn't that the INC was dishonest, per se. What it is, is that they were willing to believe anything bad about Saddam Hussein that could help their cause of regime change," said Albright, the former U.N. inspector. 

"And I think the Pentagon, particularly the hard-liners, suspended their analytical judgment in order to adopt some of these points of view and information." 

U.S. officials, however, believe Iraqi scientists and former officials will eventually open up about WMD programs. 

"Now, whether it is the mobile labs or weapons disguised as industry, we are finding ... that the capabilities were even more dispersed and disguised than we had thought," U.S. Deputy Secretary of State Richard Armitage said in an April 30 speech to the National Defense University. 

"The evidence of Saddam Hussein's programs is likely to be spread across many hundreds and even possibly thousands of sites in Iraq. It is going to take us months to find this material, but find it we will," Armitage said. 

Hampering those efforts are many contradictory reports from various U.S. military teams searching for WMD. 

For example, the U.S. Army's 1st Squadron, 10th Cavalry investigated a site at Baiji, north of Baghdad. They said they had detected nerve and blister agents in 55-gallon drums. 

Another team got the same test results. But then a third, more senior team -- known as Mobile Exploitation Team Bravo -- could not substantiate the earlier results using more sophisticated methods. 

Albright says the failure to find WMD so far raises larger concerns. 

"One of the questions about whether the U.S. government or officials lied is if the U.S. believed its own story, that there were so many weapons of mass destruction, you would expect them to be completely panicked right now, because they are not protected, and they could go easily missing and get into the hands of terrorists," he said. 

"And yet they're not panicked. So you do have to start to wonder whether the ... people who believed these stories, really were the American people and not the U.S. government." 

Publicly, U.S. officials remain steadfast in their contention that Iraq had WMD programs. 

If the United States and Great Britain are successful in proving their allegations that Iraq possessed WMD, their international credibility would be bolstered. 

But if they are unsuccessful, it raises the possibility that the Iraqis were telling the truth and that the United States and Great Britain relied on overly enthusiastic operatives on the ground.