Iraqi government investigators tracing hundreds of millions of pounds missing from late president Saddam Hussein's illicit fortune are hoping to question members of his close family.
Officials from the FBI, the US Treasury and the State Department particularly want to find ?2.2 billion (US$4.3 billion) in illegal profits that Saddam's regime is alleged to have earned from 2000 to 2003.
The profit came from an oil-for-trade pact signed with Syria that was outside the official UN administered oil-for-food program, according to official documents released to a US congressional sub-committee.
US State Department and Treasury officials claim that Syria has failed to account properly for more than US$500 million in Iraqi oil profits.
The cash, deposited in Syria's central bank, was paid to Syrian "businessmen" after Saddam's fall, sources say.
Syrian officials deny the allegations, saying that visits by US officials to Damascus in the autumn of 2003 failed to uncover any evidence of the missing cash apart from US$300 million that has already been frozen.
The UN imposed economic sanctions, including a ban on oil sales, on Iraq in 1990 after Saddam invaded Kuwait.
The oil-for- food program was launched in December 1996 to ease the impact of the sanctions on ordinary Iraqis.
The program, supervised by the 15-nation UN Security Council, authorized the government to sell oil and use the proceeds to buy civilian goods.
In a report submitted to the CIA last year Charles Duelfer, a former UN arms inspectors, estimated that Saddam had amassed US$10.9 billion "through illicit means" between 1990, when sanctions were imposed, and 2003.
The dictator is also believed to have hidden cash in accounts in Switzerland, Japan, Germany and other countries and to have invested in precious stones, possibly diamonds purchased in east Asia.
Immediately before the war of 2003, US$1.7 billion in assets in accounts held in the US in the name of the government of Iraq, the central bank of Iraq, the state organization for marketing oil, the Rafidain bank and the Rasheed bank were seized.
The Bank of England froze ?400 million in British banks.
An additional US$495 million of previously unknown assets were secured in accounts located in Lebanon.
In the immediate aftermath of his capture Saddam was said to have given his US interrogators information on the whereabouts of the billions of dollars he had siphoned from Iraq's coffers and salted away abroad.
Iyad Allawi, then a member of the Iraqi Governing Council, said that the Iraqis were searching for ?23 billion.
The money was "deposited in Switzerland, Japan, Germany and other countries under the names of fictitious companies," he said.
Barzan al-Tikriti, half-brother to Saddam, was captured in April 2003. He has been a key source for financial investigators in the US and Iraq, who now believe that close family members might hold the key.
Barzan began managing Saddam's overseas portfolio after moving to Geneva in 1983, where he served as Iraq's ambassador to Switzerland.
Raghad, Saddam's daughter, lives freely in Amman, Jordan, under the condition that she does not engage in political activities or make public statements.
King Abdullah of Jordan granted both her and her sister, Rana, asylum on humanitarian grounds after the 2003 US-led invasion of Iraq.