IRAQ: Before two murdered Americans, Eugene Armstrong and Jack Henley, can be buried their remains must undergo a detailed autopsy, writes Jack Fairweather in Baghdad
Doctors will ascertain the time of death to see how long it took for video footage of their beheadings to reach an Internet provider. They will check for internal injuries and the type of weapons that might have inflicted them.
They will even check the content of their stomachs to see what, if anything, the men may have eaten during their captivity.
Every detail is a clue that could lead investigators to their murderer, according to one US official. "As an investigator you're trying to build up a composite picture of everything that happened in their last few days in the hope that that will lead you to the murderers," he said.
But the basic work - the gathering of witnesses' statements and co-ordination with local police - is next to impossible in Iraq. In the current security climate American and British agents are rarely able to make detailed surveys of a crime scene.
For several hours after the announcement that Kenneth Bigley, Jack Hensley and Eugene Armstrong had been kidnapped from the wealthy Mansur district of Baghdad, the only people gathering evidence at the house were journalists and local policemen.
At the Alaash police station in Mansur Iraqi officers said they had still not been contacted by coalition officials.
"We spoke with several witnesses who saw the men being kidnapped, and descriptions of some of the terrorists," said Lieut Amar Jabouri.
Iraq's 120,000 police force is still at a rudimentary level of competence, with many recruits rushed into service before completing training in investigative techniques. Some officers clearly have a degree of sympathy with the aims of the resistance.
But Iraqi police say they feel hamstrung in their efforts to pursue the insurgents.
They say they have made repeated attempts to trace mobile phone calls used by known kidnap gangs in the area, but have been palmed off by Iraq's main mobile phone provider.
One officer described catching a terrorist called Ali Jasim Hamed, who had been involved in a rocket attack on the Palestine Hotel. They handed him over to US forces, who released him a few weeks later, the officer said.
Col Faroq Jabouri at Baghdad's major crimes unit said it had been made clear to him that Iraqis should stick to dealing with Iraqi cases.
That means that much American intelligence must rely on those Iraqis who volunteer information at US bases, or on paid informants. Both sources can be highly unreliable.
One US officer, who has now left Iraq, described sifting through transcripts of 20 to 30 interviews each morning.
The aim, he said, was to begin identifying cell members and command structures of terrorist networks, although often he would be dealing with local disputes between disgruntled criminal gang members. "You hear one name mentioned a few times. Then you hope you've got the first building block.," he said.
That has left much of the hunt for Abu Musab al-Zarqawi and his group down to the US military. There have been repeated air strikes on what the military refers to as "Al-Zarqawi safehouses". Commanders refer to these operations as "shaping the battle space".
They see al-Zarqawi's group as one of a myriad of Islamic extremists, former Baathists and foreign fighters that make up the rebel stronghold of Fallujah.