How DNA work in Yorkshire helped trap outback killer

IT was one of the most high-profile international murder investigations of recent years: the killing of British backpacker Peter Falconio in the Australian outback.

And it was an expert from the Forensic Science Laboratory at Wetherby who helped solve it.

Dr John Whitaker, a senior forensic scientist at Wetherby, was the man who made the DNA matches which ultimately convicted 47-year-old Bradley Murdoch of Peter's murder, and of the abduction and assault of Peter's girlfriend Joanne Lees.

Peter and Joanne had been travelling in their camper van 175 miles north of Alice Springs, Australia, when they were flagged down on July 14, 2001 by the driver of a white truck.

Peter went around to the back of his camper van to speak to the driver - and Joanne heard a gunshot.

The driver reappeared and tied Joanne up before putting her in his truck. She managed to escape and hid among bushes before flagging down a passing lorry. Peter's body was never found.

The hunt for his killer was long and painstaking. Ultimately, it was DNA that was to prove Murdoch's downfall.

Dr Whitaker, who was part of a British forensic science services team who developed an advanced new DNA technique, DNA Low Copy Number or LCN, was asked by Northern Territories police to analyse DNA samples found on the gear stick and steering wheel of Peter's van - and on the home-made "handcuffs" that had been used to bind Joanne's hands.

The samples were sent to Wetherby for analysis - and DNA from deep inside the black plastic cables used to tie up Joanne proved to be Murdoch's. A partial DNA profile matching Murdoch was also obtained from the gear stick of Peter's van.

Dr Whitaker testified in a courtroom in Darwin, Australia, that the DNA profile obtained from the handcuffs was 100 million times more likely to have come from Murdoch than from someone else.

Murdoch, who denied the killing, was found guilty and sentenced last month to at least 28 years in prison.

Dr Whitaker is one of about 250 scientists and technicians at Wetherby - which is one of 11 Forensic Science Service Ltd facilities in the country.

It is one of only two centres, however, where the new DNA LCN technology is used - meaning that many of the most serious and high-profile cases are referred there.

Scientists at Wetherby do use other forensic techniques, Dr Whitaker says - analysing footprints, strands of hair and even flakes of paint, for example, that may be able to place a suspect at the scene of the crime.

But it is DNA profiling that has really revolutionised forensic science, he says - and which is proving such an effective weapon in the fight against crime.

As the Home Office revealed this week, the number of crimes being solved with the help of DNA technology has quadrupled in thepast five years alone. But how does DNA profiling work? And, more important, how reliable is it?

How DNA profiling works

DNA is the chemical that acts as our genetic building block and that determines the way we all look and even behave, Dr Whitaker says.

It is in every cell, every drop of sweat, every blood corpuscle and hair follicle in our bodies - the ultimate genetic "fingerprint".

The vast majority of our DNA is identical with that of everybody else: but there are certain sites on the DNA molecule which are widely different between different people, Dr Whitaker says.

It is these sites that scientists target when making a profile.

The key differences between people are in how long these tiny sites on the DNA molecule are.

Using the DNA LCN technique developed by Dr Whitaker and others, only a tiny sample of DNA from a crime scene is needed. A drop of blood or semen no bigger than a matchhead or a single hair root will do.

Even skin cells rubbed off when somebody touched something - like that plastic cable used to bind Joanne Lees - can yield a result.

DNA samples are brought to Wetherby, where the DNA is "copied" and amplified in a tiny tube, to provide a large enough sample to work on.

Using sophisticated equipment in the laboratory, scientists at Wetherby are then able to measure the length of each of ten particular sites - the sites that differ between different people - on DNA molecules taken from a given sample.

A DNA profile is then made by assigning two numbers for each of these sites, depending on their length - yielding a 20 digit number.

It is this number that is compared with the number obtained from a DNA analysis of a sample taken from a subject.

It can also be compared with DNA profiles - again in the form of sequences of 20 numbers - stored on the national DNA database.

Dr Whitaker insists that the use of DNA profiling is 100 per cent reliable. Huge strides have been made in eliminating the risks of a mistake caused by a DNA sample being contaminated by DNA from someone else, he says.

Scientists working on the samples wear masks and gloves: and their own DNA is sequenced, so that if it does get mixed up with a sample, it can be identified and discounted when making a profile.

No DNA sample can be said to be absolutely unique, he admits. "But we know... that if we get a full profile, the chance of getting that from somebody other than the person would be about one in one billion," he says.

Is the UK's DNA database growing too fast?

There is no doubt that DNA profiling is effective.

But there are concerns at the rate at which the UK's DNA database is growing.

By April 2008, it is expected to include the DNA of 4.2 million people - seven per cent of the UK's population. That makes it proportionally by far the largest DNA database in the world.

Even more worrying, over one third of all black men in the UK are on the database, according to one national newspaper: compared with fewer than one in ten of white men. The law at the moment allows the DNA of anybody arrested for a serious crime to be kept on the national database - whether or not they were found guilty, or even charged. So are we going too far, too fast?

YES...

The rapid growth of the DNA database "threatens our hard won freedoms and rights", according to Frank Ormston, of the RESPECT unity coalition in York.

The fact that the DNA of anybody arrested for a serious crime can be kept on the database even if they are never charged damages the presumption of innocence, one of the "cornerstones of British justice", Mr Ormston says. "It would seem the state now assumes we are all guilty."

DNA testing is not infallible, he adds. "Once a sample of (often poor quality) DNA is recovered from a crime scene, an expert gives his or her opinion as to the probability of it having not come from the accused. In other words, purportedly incontrovertible evidence is open to misinterpretation.

"The misinterpretation of cutting-edge forensic evidence led to the wrongful conviction and imprisonment of the Birmingham Six. Over-reliance on DNA evidence may result in similar miscarriages of justice."

The disproportionally high number of black men on the database is a real cause for concern, he says. He is also worried about the future. "A future government which believes criminality is genetically-determined could begin labelling people as criminals from birth."

NO...

Home Secretary Charles Clarke admits it is inevitable that more and more people will end up on the database - but insists safeguards are in place.

"There's a whole set of legal requirements about the circumstances in which DNA can be used," he told BBC Radio 4.

DNA profiling was about solving crime, he said. "We have one of the best developed systems in the world to be able to do that and as long as it is properly used... I think it's a technique we should use," he said.

Former policeman turned Conservative MP for Ryedale John Greenway says the current rules on whose DNA should be added to the database struck the right balance.

He would be against extending the database to include everybody in the country - with your DNA added to the database at birth, for example.

But he saw no problem with the DNA of people who had been arrested in connection with a serious offence being kept - even if they were never charged. Anyone who is innocent has nothing to fear, he insists.

Les Coverdale, secretary of North Yorkshire Police Federation, says as well as helping to solve serious crimes, the DNA database is also a deterrent.

If a potential criminal knows his DNA is held on file, he or she may think twice about committing a crime.

Snared by science

When Andrew Bailey raped a young woman in Flaxley Road, Selby, on February 1 2004, he left few clues behind him. The victim did not know her attacker, and Bailey even took her mobile phone so as not to leave fingerprints.

But local people tipped off police that Bailey might have been responsible. Scientists at Wetherby matched fibres on the woman's clothing with a fleece jacket from Bailey's home. And forensic scientists from Birmingham then used an innovative Y-chromosome DNA technique to match Bailey's DNA with swabs from the victim. Bailey was convicted and jailed for seven years.

Former soldier Andrew William Rome was jailed last year for the brutal rape of a York woman at her flat in Heworth more than 20 years earlier - after he was traced using DNA techniques.

For years, it looked as though Rome had got away with his crime.

Then, in 2004, he was arrested for hitting a 12-year-old girl. His DNA matched DNA found at the York rape scene in 1984. Rome admitted the rape and was jailed for six-and-a-half years.

Updated: 09:13 Friday, January 06, 2006