A single strand of hair can determine victim's fate

Even when presented with just a fraction of this material, forensic experts can discover a huge amount about what has happened to a person – whether they were the victim of a murder or an accident. It can also help build up a background picture of the victim – where they may be from, what kind of lifestyle they led, and possibly where they have recently visited.

Armed with just a few snippets of general information, it could help detectives establish what happened, when, and maybe even why.

It is this kind of partial evidence that is now being examined by experts in Tayside after a severed head and two hands were found washed up on a beach in Arbroath.

The work of forensic scientists has been glamorised in television programmes like CSI: Crime Scene Investigation and Silent Witness. These shows are a far cry from the meandering investigations of bygone TV sleuths, such as Miss Marple and Columbo, who usually relied on gentle questioning and maybe a glove dropped at the crime scene to find their perpetrator.

Now the viewing public expect DNA profiling, microscopic examination and hair and tissue analysis as standard.

In previous cases, experts have been able to use sophisticated technology to reveal detailed information from a person's hair. The composition of the hair can suggest the types of food someone has eaten in the months before their death. It can also indicate the places where a person has visited in the previous months, based on exposure to environmental factors.

Such chemical and isotope analysis has been pioneered by Stuart Black, an expert in environmental radioactivity at Reading University. But forensic experts start with the most basic techniques, before moving on to more innovative methods.

Professor Anthony Busuttil, emeritus professor of forensic medicine at Edinburgh University, knows only too well the value of both new and more basic techniques in the search for answers.

As a forensic medical examiner to Lothian and Borders Police, he has been involved in thousands of cases of sudden and unexplained deaths. He has also assisted in many high-profile investigations, including the Lockerbie disaster and Dunblane Primary School massacre.

Prof Busuttil said the first task of any investigator faced with a number of individual body parts would be to establish if they all came from the same person.

"This can be done by extracting the DNA and seeing if they all match," he said. "Also, once you have the DNA, you can start searching to see if there is a match for any missing person or for anyone else whose DNA is on record."

He said such DNA samples could take a week to process, meaning investigators had time to use more basic techniques to try to identify the victim.

Police will look at missing persons' files, check for fingerprints and examine dental records to try to get an identity.

Fibres and other types of material found tangled in the hair could reveal where the head had come from.

"It may also be worth swabbing the inside of the nose to see if there is any pollen inside which could narrow down the area where the person has recently been," the professor said.

Body parts can also give clues to the cause of death. He said: "The next step would be to look at how the body parts were separated from the body. If the body was in the water, could they have been cut off by a propeller of a boat? Or if they were obviously cut off, that would be an indicator to suggest foul play."

Prof Busuttil said the head and hands might yield clues as to how a person was killed.

"If the person has been in a fight, there might be marks and scratches on the hands. If the head has signs of being bashed, that could also point to the cause of death," he said. "They can also X-ray the head to reveal any evidence of fractures."

Prof Busuttil said that if body parts were found wrapped in a plastic bag or other material, this could reveal clues to the killer, such as finger prints.

In the case of the body parts found in Arbroath, he said the fact that two hands and a head had been found in such close proximity made it likely they were dumped on the beach rather than being washed ashore. If they had been dumped in the sea, the chances of them being washed up together were slimmer.

Experts also have a range of more complex methods at their disposal to find out more about a victim in cases where only a couple of body parts have been found.

Prof Busuttil said only after exhausting the most basic techniques would such methods be used.

"The bone and hair may also reveal more details, but analysing these is much more lengthy and painstaking work," he said. "This is usually done when other methods have failed to find an identity.

"The hair can be used to find out the drug history of the individual, whether they smoked, used cannabis or heroin. The bone could also help narrow down the location of where the person was brought up. This is because water in different areas contains different levels of minerals, which affect the development of the bones."

He said samples from the body parts might be able to reveal if someone had died from some form of poisoning, but this could be difficult as there was not likely to be much blood to test.

"In this case, they could use brain tissue or eye fluid or a small sample of blood, if there is any left," Prof Busuttil said, adding that it could many weeks to get the results of such tests.

Investigators in Arbroath will be using all the tools at their disposal to find out the tragic story that led to two children finding a severed head on the beach.

While such cases are not common, they demonstrate the importance of developments in forensic science in helping investigators answer some very difficult questions and bring closure for families.

"There are loads of things one can do in these types of investigation," Prof Busuttil said. "We start with the easy bits and work our way through to the more esoteric."

The many mysteries solved by minute examination of bodies

FORENSIC science has proved invaluable in a series of high- profile police investigations in recent years.

In December 1999, the discovery of severed limbs in Loch Lomond sparked a major police inquiry.

Fears of a serial killer on the loose grew a few days later when a head was washed up on Barassie Beach, Troon.

Police used DNA and other tests to identify the victim as 18-year-old Barry Wallace. Further forensic evidence led police to William Beggs, who was jailed for the murder of the teenager. In 2001, the discovery of a young boy's headless and limbless torso in the River Thames led to police using pioneering forensic methods in efforts to identify him.

It was eventually discovered that the boy – named Adam – came from a narrow coastal strip of Nigeria. A post-mortem examination found that he bled to death, while an analysis of his stomach contents led police to believe that the boy was poisoned for a ritual sacrifice in which his throat was cut.

In an unusual case in Dorset in 2002, Heather Barnett was found stabbed to death. Cut hairs from another person's head were found in her hand.

Last year a chemical and isotope analysis of the strands revealed the owner changed diet twice in the three months before the hair was cut.

They also visited an area in eastern Spain and/or the Marseille to Perpignan area of southern France, some eleven weeks before the hair was cut.

They then visited the urban area of Tampa in Florida, southern USA, for eight days some weeks before the hair was cut.