The Iraqi scientist who headed Saddam Hussein's (searchlong-range missile program has fled to neighboring Iran, a country identified as a state sponsor of terrorism with a successful missile program and nuclear ambitions, U.S. officers involved in the weapons hunt told The Associated Press.

Dr. Modher Sadeq-Saba al-Tamimi's (search) departure comes as top weapons makers from Saddam's deposed regime find themselves eight months out of work but with skills that could be lucrative to militaries or terrorist organizations in neighboring countries. U.S. officials have said some are already in Syria and Jordan.

Experts long feared the collapse of Saddam's rule could lead to the kind of scientific brain-drain the United States tried to prevent as the former Soviet Union collapsed. But the Bush administration had no plan for Iraqi scientists and instead officials suggested they could be tried for war crimes.

"There are a couple hundred Iraqis who are really good scientists, particularly in the missile area," said Jonathan Tucker, a former U.N. inspector now with the Center for Nonproliferation Studies (searchat the Monterey Institute in California. "In the chemical and biological areas, their work wasn't state of the art but it was good enough to be of interest to other countries."

Only now is the State Department exploring the possibility of a government-funded program to block a scientific exodus and prevent Iraqis from doing future research in weapons of mass destruction. Initial cost estimates for the program run about $16 million, according to a Nov. 3 draft proposal obtained by AP.

Two members of the Pentagon's Defense Intelligence Agency (searchinvolved in questioning scientists in custody told AP the Iraqis continue to deny the existence of illicit weapons programs in Iraq. Dozens of Iraqi scientists have been questioned and less than 30 remain in custody. All of them, including senior members of Saddam's regime, have been subjected to lie-detector tests, which have come up clean on weapons questioning, the DIA officers said.

But U.S. scientists and weapons experts, who all spoke on condition of anonymity, said they're having trouble finding some Iraqi experts in Iraq and have no way of tracking ones they've met.

"They could leave Baghdad tomorrow and we'd never know," said one senior official involved in the hunt. "Very few are obligated to tell us where they're going or what they're up to."

U.N. inspectors spoke with Dr. Modher in Baghdad a week before the U.S.-led war began on March 20. Two U.S. weapons investigators say they believe he crossed the Iraq-Iran border on foot at least two months after U.S. forces took Baghdad.

His activities in Iran are unclear and may explain why his disappearance hasn't been publicly disclosed. The CIA declined to discuss its efforts with Iraqi scientists or identify individuals.

Thought to be in his mid-50's, the Czech-educated scientist specialized in missile engines. He met numerous times with U.N. inspectors during the 1990s and earlier this year when he argued that the Al-Samoud missile system under his command wasn't in violation of a U.N. range limit. The inspectors determined otherwise when tests showed it could fly more than 93 miles. They quickly began destroying the Iraqi stock, much to his frustration.

"Dr. Modher was declared by Iraq to have been one of the principal figures in their missile programs," said Ewen Buchanan, spokesman for the U.N. inspectors.

In the late 1980s, Modher headed up the Iraqi military's Project 1728, part of an effort to produce engines for longer-range missiles.

He was the protege and favored colleague of Iraqi Lt. Gen. Hussein Kamel, Saddam's right-hand man and son-in-law who briefly defected to Jordan in 1995. There, Kamel told U.N. inspectors during interrogations about his work and Dr. Modher's efforts to build a missile powerful enough to strike most major European cities.

According to the interrogation transcripts, Kamel said Modher and a nuclear physicist named Mahdi Obeidi both took work and documents from their offices. U.N. inspectors investigated the claim but found nothing.

In July of this year, Obeidi gave the CIA a stack of papers and a piece of equipment that had been buried in his backyard for 12 years. In return, he has become the only Iraqi scientist allowed to move to the United States since the beginning of the U.S. occupation.

Other than Obeidi, who is living along the East Coast with his family, another scientist known to have left the country is Jaffar al-Jaffer who founded Iraq's nuclear program in the 1980s. He's in the United Arab Emirates, where U.S. troops are stationed, and has been questioned by U.S. and British intelligence officials.

But Jaffar, like a handful of senior scientists being held by U.S. forces in Iraq, hasn't provided any information on the whereabouts of suspected chemical, biological or nuclear weapons. While President Bush said he launched the war to disarm Iraq of its deadly arsenal, such weapons remain elusive.

David Kay, the chief weapons hunter, has said his teams so far have found new information on Iraqi missile systems. But a conversation with Modher could have cleared up unanswered questions about Iraq's true capabilities for delivering weapons of mass destruction.

Modher traveled to Germany in 1987 to buy high-tech equipment through H & H Metalform, a company whose senior officers were later tried in Germany and found guilty of violating the country's export control laws, U.N. inspectors said.

The equipment enabled Iraq to make components for Scud missiles similar to the ones they later fired at Israel and Saudi Arabia during the 1991 Gulf War.

When that conflict ended, Iraq faced U.N. sanctions forbidding it from purchasing any new weapons-making equipment.

But four years later, Modher was caught by U.N. inspectors when he inquired about Russian-made gyroscopes from a Palestinian middleman. At the time, Tariq Aziz, then Iraq's deputy prime minister, told U.N. inspectors Modher had acted on his own and would be punished for breaking sanctions. He allegedly spent 2 1/2 years in jail.

Kay told reporters in Washington last month that "senior Iraqi officials, both military and scientific" had moved to Jordan and Syria, "both pre-conflict and some during the conflict, and some immediately after the conflict."

He didn't mention Iran, although its long, shared border with Iraq has been an easy crossing point for militants and Shiite pilgrims headed to Iraqi shrines.

Jordanian and Syrian officials dismissed claims that wanted Iraqis are inside their countries and Kay has offered no names of those believed to have fled.

But signs of an exodus have led to a renewed push by nonproliferation experts and government officials to keep the scientists from wandering.

The 11-page State Department plan aimed at preventing Iraqi scientists from fleeing is entitled "The Science Technology and Engineering Mentorship Initiative for Iraq."

Such initiatives are critical but late, said Tucker of the Monterey Institute.

"This is something that should have been done immediately after the war ended," he said. "The initial approach, which was to treat them as criminals and threaten them with prosecution only makes scientists want to leave or stay away."