Identifying the victims

Bodies could remain buried in rubble for months

The task of identifying victims of the New York attacks is a complex and painstaking one which may take months to complete.

In some instances it will only be possible to identify people from the smallest of clues.

Many people will have been so badly injured that little physical trace will remain.

Bodies will still be there, probably, come Christmas

Dr Michael Bade

Other bodies could remain buried under rubble for a long time - in some cases possibly even months.

The fastest way to identify victims is by matching up fingerprints, x-rays or dental records.

A single tooth can often be enough. In fact, each filling has a sufficiently distinct shape to make identification possible.

Dr Judith Hinchliffe, a forensic dentist in Sheffield, UK, told BBC News Online that it would a massive logistical task to obtain dental records for all those who were missing.

She said: "Fragmentation and burning will not work in the forensic dentists' favour, but there will be quite a few people who they will be able to identify."

If this form of identification fails, an important source of information will be the missing persons reports that are still being completed by anguished relatives.

These provide identifying details such as shoe size, belt size, blood type and mother's maiden name.

The more specific detail that investigators have, the better their chances of making a positive identification.

It may be that somebody can be positively identified by an old bullet wound, by their pacemaker or by the colour that they painted their fingernails.

Information on each person reported missing is being entered into a database.

DNA fragments

Gene analysis could provide vital clues

Where these techniques fail, forensic experts will be able to use state-of-the-art genetic profiling to try to get a positive identification.

Relatives are being asked to collect personal items that may contain tiny DNA fragments of their loved ones.

These include toothbrushes, hair brushes, unwashed clothes, even a licked envelope.

This genetic material can be used by forensic experts to match against tissue samples. Each person's DNA is unique to them.

Already forensic experts have begun to analyse the DNA contained in some of the remains of victims.

Not only will this information help eventually to identify the victims, it can be used to aid the task of matching up different body parts - each of which is arriving at city morgues in a separate bag with its own number.

The process of identifying the victims in New York is being overseen by the city medical examiner's office. US domestic forensic experts are being aided by specialists from around the world.

A Belgian team of burns specialists and experts in victim identification has already arrived in the US.

They will be joined by a police team from the UK to help identify British victims.

Teams of experts from France, Sweden, Ireland, Spain, Italy, Finland and the Netherlands have also been mobilised and put on standby.

Biggest ever

Dr Michael Bade, chief forensic pathologist for the New York State Police, said the task of identifying the victims was probably the biggest of its type ever undertaken.

However, he is confident that eventually every body or part of a body that is recovered will be identified.

He said: "It is not as overwhelming as it sounds. The bodies are going to be coming up a little bit at a time.

"It is not a thousand bodies at one time. Bodies will still be there, probably, come Christmas."