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TECHNOLOGY - DNA

IAN MUNRO
The Age, Sunday 24 February, 2002

TECH

"It went in one ear and out the other," Trace, of Salisbury Downs north of Adelaide, says. "I just thought rah rah rah, it being such a long period of time, they'll do some tests, talk to a couple of people."

He thanked them for the courtesy call and thought no more of it.

About two months later, they rang his mobile phone again. This time they were parked outside a house in Maitland, New South Wales, and they were about to enter the property to arrest Cheryl's killer.
Rodney Keith Winters was interviewed several times by police in the threeyears after the 1982 murder, but it was not until DNA tests in 1995 linked him to the scene that he was arrested, and not until late 1996, when further tests had eliminated the possibility of a second person being involved in the attack on Cheryl Trace, that he admitted his guilt.

"It's a long period of time not knowing who (was responsible). It was fantastic to finally catch the guy," Trace says. "We had a little bit of regret for his family. He was married with young children then. They had not known what he had done. He destroyed two families."

Last year, evolving DNA technology enabled the past to reach out to another killer when Sydney businessman Wayne Edward Butler was convicted of a 1983 murder at Brampton Island. The prosecution case relied on a semen stain on the towel that covered the body of tourist resort worker Celia Douty when she was found dead. Butler had long been a suspect, but it was not until DNA tests established the probability that the stain was his that he was charged.

In the United States, DNA tests have exonerated nine death row inmates and 70 prisoners have been cleared. In Queensland last year, a man successfully appealed against a conviction for rape when DNA evidence not presented at his trial established his innocence.

Against this sort of background, DNA testing assumes a magic aura, offeringan extraordinary certitude about the dispensing of justice. A mass screening of Victorian prisoners, which is still unfolding, already has linked 113 people to 297 offences, including several homicides, five rapes and numerous burglaries and robberies.

Jeremy Gans, a senior lecturer at Melbourne University Law School, says all the DNA in a person's body is identical and, with the exception of identical twins, everyone has different DNA. This is what makes the process so conclusive.

"They don't look at the entirety of the genome (human genetic material) whenthey test it. They look only at a tiny part of the DNA ... the bit we don't share."

While DNA determines inherited characteristics, such as hair and eye colour, human cells include much DNA that has no clear role and is described as "junk DNA". This is the material forensic scientists examine.

In Victoria, nine points, or loci, of this junk DNA are checked againstdatabases that show how common each DNA type is within the population. This makes it possible to estimate the odds of a match between two profiles. A match on one point that may have 10 known variations is interesting. A match on a second point, also with 10 known variations, is more interesting still. A match on all nine is long odds indeed.

While it is possible to say that a particular sample clearly does not come from a specific individual, current technology does not allow an analyst to conclude that a sample could have come from one person only, and no other. So, a match is expressed only in degrees of probability.

Despite its role in solving "cold" cases, DNA is mostly just one moreelement to be considered in a crime, like opportunity and motive. It is, arguably, more conclusive in eliminating suspects than in confirming them.

"It's a great elimination tool. It's just as important to us within an investigation to eliminate suspects as to convict someone," says the head of the Victoria Police crime intelligence division, Detective Inspector Doug Cowlishaw.

The growing importance of DNA sampling increases the importance of managingcrime scenes and not compromising evidence. In Victoria, there are 37 crime scene specialists trained to gather material.

Cowlishaw says police view DNA to be as important as a deterrent to future offences as it is an aid to solving crime. One of the first offenders tested in Victoria, a paedophile who abducted a nine-year-old girl, asked what the sampling meant for him. "I said, 'If you ever commit another offence, you will have to wear a spacesuit,' " Cowlishaw recalls.

"Because of the way DNA works and the trace samples you take from the scene... there's a high chance they will leave something. They'll shed some skin, some hair, they sweat on something, they spit, blood obviously. It doesn't take much."

The medical director of the Victorian Institute of Forensic Mental Health, Professor Paul Mullen, says the impact of DNA as an investigating tool should not be overstated. Rapists who plan their attacks, for example, will wear condoms, robbers will take care not to leave gloves or masks behind.

He adds that it is also the case, however, that much offending is impulsive,disorganised and carried out under the influence of drugs or alcohol.

"There's no doubt that recidivist-type offences are those by people who plan carefully," Professor Mullen says. "They are more likely to change the pattern of their criminality.

"The risk of detection is one of the things that affects crime, but it isonly one of them. Unfortunately, most offenders out there are not doing a cost-benefit analysis."

Despite the precautions some offenders might take, Cowlishaw sees DNA profiling as a powerful deterrent. "Of course, they will change their manner of offending. The same question was asked of fingerprints 100 years ago. Fingerprints are still catching as many crooks."

Career criminals, for whom going to jail is like paying tax, may not be muchaffected by it, but young or occasional offenders seem strongly affected, Cowlishaw says. "My view would be any percentage affected would be a win."

One of the advances in DNA typing has been the ability to replicate, or amplify, small quantities of DNA in order to have sufficient material for testing, so a trace of saliva on a cigarette butt may yield sufficient material for typing. In Victoria, samples have been taken specifically for DNA testing since 1989, although as Winters' conviction showed, older DNA samples can be effective for identification. A sample about 20 years old is among those for which prisoners are still being tested in Victoria today.

Cowlishaw says that, as a matter of policy, DNA is only part of a brief ofevidence - it may trigger an investigation or just add another piece to a puzzle. "DNA is about telling you a truth and that truth may be that that person was at that place at that particular moment when this offence was committed. It doesn't tell you he committed the offence."

Police say very few prisoners, when confronted with DNA evidence, plead not guilty, but Gans says mass testing programs like Victoria's present new problems. He says that it sets up the possibility that DNA may be the only evidence for offences, which even the perpetrator may have forgotten.

"Until the rise of databases, most uses of DNA have been for people wherethere's other evidence already in existence. Once the database starts to generate totally unsuspected people as the prime suspect, the danger is that will be the only evidence that's brought up in court, or that other evidence brought up in court is tainted by that," Gans says.

"I'm worried by the possibility of false confessions. People make false confessions on far shoddier evidence than DNA. DNA evidence is very good evidence for the most part. If I am told there's a one-in-a-million match (against me), I'd have to think about going along with that and getting the benefit of a guilty plea."

He adds that, because of its role in exposing wrongful convictions in thecriminal justice system, there is a danger DNA may be venerated as more foolproof than it is. If it is very good evidence for the most part, it is nonetheless not flawless evidence.

There are no known cases of false DNA matches in Australia, but in Britain in 1999 police charged a man with burglary following a database match that was later shown to be false using a more refined DNA technique. The initial match was said to be the result of a one-in-37-million coincidence. The same year, in New Zealand, a man on a DNA database as a victim of violent crime was linked to two murders when his sample contaminated the murder evidence in a laboratory.

"As someone who has to teach courses about the other failings of the criminaljustice system, DNA is pretty good by comparison, but then people thought the earlier system was good by comparison with what went before that," Gans says.

"Too much confidence is the danger in DNA."

Human error, breaks in the chain of evidence and laboratory failures are theweaknesses in DNA evidence, rather than the science itself. But increasing automation may limit even these.

According to a US National Institute of Justice report, within a decade investigators may be equipped with portable instruments able to read DNA evidence at a crime scene. Connected to a remote database, their readings would make for rapid identification and elimination of suspects.

In time, it may be possible to determine physical traits of an individualfrom their DNA, helping to narrow the search for a suspect.

For now, there remain areas of judgment and, hence, potential error. Gans says the chemical processes involved in testing can go awry and scientists have to be able to recognise anomalies this might create. Judgment calls may also be needed in recognising mixed or degraded samples.

"One of the great things about DNA, and this is in contrast to most otherscientific evidence that's used in court, is that DNA science is a highly developed area of scientific endeavour," he says. "That's in contrast to things like hair analysis, voice recognition, which are infant sciences - some call them junk sciences.

"DNA is much better than that, and it's getting better."

Putting crime to the test

THIRTEEN years after his sister, Cheryl, was raped and murdered, police rang Guy Trace. The first time, they told him they were going to run some new DNA tests on evidence found with his sister's body.

"It went in one ear and out the other," Trace, of Salisbury Downs north of Adelaide, says. "I just thought rah rah rah, it being such a long period of time, they'll do some tests, talk to a couple of people."

He thanked them for the courtesy call and thought no more of it.

About two months later, they rang his mobile phone again. This time they were parked outside a house in Maitland, New South Wales, and they were about to enter the property to arrest Cheryl's killer.
Rodney Keith Winters was interviewed several times by police in the threeyears after the 1982 murder, but it was not until DNA tests in 1995 linked him to the scene that he was arrested, and not until late 1996, when further tests had eliminated the possibility of a second person being involved in the attack on Cheryl Trace, that he admitted his guilt.

"It's a long period of time not knowing who (was responsible). It was fantastic to finally catch the guy," Trace says. "We had a little bit of regret for his family. He was married with young children then. They had not known what he had done. He destroyed two families."

Last year, evolving DNA technology enabled the past to reach out to another killer when Sydney businessman Wayne Edward Butler was convicted of a 1983 murder at Brampton Island. The prosecution case relied on a semen stain on the towel that covered the body of tourist resort worker Celia Douty when she was found dead. Butler had long been a suspect, but it was not until DNA tests established the probability that the stain was his that he was charged.

In the United States, DNA tests have exonerated nine death row inmates and 70 prisoners have been cleared. In Queensland last year, a man successfully appealed against a conviction for rape when DNA evidence not presented at his trial established his innocence.

Against this sort of background, DNA testing assumes a magic aura, offeringan extraordinary certitude about the dispensing of justice. A mass screening of Victorian prisoners, which is still unfolding, already has linked 113 people to 297 offences, including several homicides, five rapes and numerous burglaries and robberies.

Jeremy Gans, a senior lecturer at Melbourne University Law School, says all the DNA in a person's body is identical and, with the exception of identical twins, everyone has different DNA. This is what makes the process so conclusive.

"They don't look at the entirety of the genome (human genetic material) whenthey test it. They look only at a tiny part of the DNA ... the bit we don't share."

While DNA determines inherited characteristics, such as hair and eye colour, human cells include much DNA that has no clear role and is described as "junk DNA". This is the material forensic scientists examine.

In Victoria, nine points, or loci, of this junk DNA are checked againstdatabases that show how common each DNA type is within the population. This makes it possible to estimate the odds of a match between two profiles. A match on one point that may have 10 known variations is interesting. A match on a second point, also with 10 known variations, is more interesting still. A match on all nine is long odds indeed.

While it is possible to say that a particular sample clearly does not come from a specific individual, current technology does not allow an analyst to conclude that a sample could have come from one person only, and no other. So, a match is expressed only in degrees of probability.

Despite its role in solving "cold" cases, DNA is mostly just one moreelement to be considered in a crime, like opportunity and motive. It is, arguably, more conclusive in eliminating suspects than in confirming them.

"It's a great elimination tool. It's just as important to us within an investigation to eliminate suspects as to convict someone," says the head of the Victoria Police crime intelligence division, Detective Inspector Doug Cowlishaw.

The growing importance of DNA sampling increases the importance of managingcrime scenes and not compromising evidence. In Victoria, there are 37 crime scene specialists trained to gather material.

Cowlishaw says police view DNA to be as important as a deterrent to future offences as it is an aid to solving crime. One of the first offenders tested in Victoria, a paedophile who abducted a nine-year-old girl, asked what the sampling meant for him. "I said, 'If you ever commit another offence, you will have to wear a spacesuit,' " Cowlishaw recalls.

"Because of the way DNA works and the trace samples you take from the scene... there's a high chance they will leave something. They'll shed some skin, some hair, they sweat on something, they spit, blood obviously. It doesn't take much."

The medical director of the Victorian Institute of Forensic Mental Health, Professor Paul Mullen, says the impact of DNA as an investigating tool should not be overstated. Rapists who plan their attacks, for example, will wear condoms, robbers will take care not to leave gloves or masks behind.

He adds that it is also the case, however, that much offending is impulsive,disorganised and carried out under the influence of drugs or alcohol.

"There's no doubt that recidivist-type offences are those by people who plan carefully," Professor Mullen says. "They are more likely to change the pattern of their criminality.

"The risk of detection is one of the things that affects crime, but it isonly one of them. Unfortunately, most offenders out there are not doing a cost-benefit analysis."

Despite the precautions some offenders might take, Cowlishaw sees DNA profiling as a powerful deterrent. "Of course, they will change their manner of offending. The same question was asked of fingerprints 100 years ago. Fingerprints are still catching as many crooks."

Career criminals, for whom going to jail is like paying tax, may not be muchaffected by it, but young or occasional offenders seem strongly affected, Cowlishaw says. "My view would be any percentage affected would be a win."

One of the advances in DNA typing has been the ability to replicate, or amplify, small quantities of DNA in order to have sufficient material for testing, so a trace of saliva on a cigarette butt may yield sufficient material for typing. In Victoria, samples have been taken specifically for DNA testing since 1989, although as Winters' conviction showed, older DNA samples can be effective for identification. A sample about 20 years old is among those for which prisoners are still being tested in Victoria today.

Cowlishaw says that, as a matter of policy, DNA is only part of a brief ofevidence - it may trigger an investigation or just add another piece to a puzzle. "DNA is about telling you a truth and that truth may be that that person was at that place at that particular moment when this offence was committed. It doesn't tell you he committed the offence."

Police say very few prisoners, when confronted with DNA evidence, plead not guilty, but Gans says mass testing programs like Victoria's present new problems. He says that it sets up the possibility that DNA may be the only evidence for offences, which even the perpetrator may have forgotten.

"Until the rise of databases, most uses of DNA have been for people wherethere's other evidence already in existence. Once the database starts to generate totally unsuspected people as the prime suspect, the danger is that will be the only evidence that's brought up in court, or that other evidence brought up in court is tainted by that," Gans says.

"I'm worried by the possibility of false confessions. People make false confessions on far shoddier evidence than DNA. DNA evidence is very good evidence for the most part. If I am told there's a one-in-a-million match (against me), I'd have to think about going along with that and getting the benefit of a guilty plea."

He adds that, because of its role in exposing wrongful convictions in thecriminal justice system, there is a danger DNA may be venerated as more foolproof than it is. If it is very good evidence for the most part, it is nonetheless not flawless evidence.

There are no known cases of false DNA matches in Australia, but in Britain in 1999 police charged a man with burglary following a database match that was later shown to be false using a more refined DNA technique. The initial match was said to be the result of a one-in-37-million coincidence. The same year, in New Zealand, a man on a DNA database as a victim of violent crime was linked to two murders when his sample contaminated the murder evidence in a laboratory.

"As someone who has to teach courses about the other failings of the criminaljustice system, DNA is pretty good by comparison, but then people thought the earlier system was good by comparison with what went before that," Gans says.

"Too much confidence is the danger in DNA."

Human error, breaks in the chain of evidence and laboratory failures are theweaknesses in DNA evidence, rather than the science itself. But increasing automation may limit even these.

According to a US National Institute of Justice report, within a decade investigators may be equipped with portable instruments able to read DNA evidence at a crime scene. Connected to a remote database, their readings would make for rapid identification and elimination of suspects.

In time, it may be possible to determine physical traits of an individualfrom their DNA, helping to narrow the search for a suspect.

For now, there remain areas of judgment and, hence, potential error. Gans says the chemical processes involved in testing can go awry and scientists have to be able to recognise anomalies this might create. Judgment calls may also be needed in recognising mixed or degraded samples.

"One of the great things about DNA, and this is in contrast to most otherscientific evidence that's used in court, is that DNA science is a highly developed area of scientific endeavour," he says. "That's in contrast to things like hair analysis, voice recognition, which are infant sciences - some call them junk sciences.

"DNA is much better than that, and it's getting better."