In the United States – where else – a company has invented a new security device. It is a can of yellow paint. Like mace or capsicum, you spray it at your attacker.
But this is a paint with a difference. The paint gets on the skin and in the hair and is so irritating that the attacker attempts to brush it off as he flees.
When he brushes it off he leaves hair and skin entangled in the paint. From these, a DNA fingerprint can be taken. And each can of paint is unique, so attacker and victim are linked.
But what is the point of having a DNA fingerprint unless it can be matched to a named person? For that, you need a database of DNA fingerprints to match the DNA fingerprint taken from the yellow paint and for a match against a named person in the database.
This week the ACT pushed for as wide a database as possible, while other states and territories thought the database should be restricted.
But first to a brief explanation.
DNA is the huge molecule in cells that contains the genetic information of life. It is in all forms of life. The fingerprinting technique was developed in 1984 and later improved so that you can now replicate even a tiny amount of DNA so you have enough to get a fingerprint. Every individual has unique patterns of sequences along the DNA. (Only identical twins have identical patterns.) These sequences do not contribute to genetic traits. Enzymes are used to cut and strand the DNA. They are then hit with some radioactive material that latches on to particular sequences and causes an exposure on x-ray film. The result is like the illustration., like a bar code. The illustration shows the DNA fingerprint from blood (or hair) at the crime scene in the middle and the DNA fingerprint of seven suspects. Suspect No 3 has a perfect match.
That tells us with 99.9999 per cent certainty that the blood (or hair) in the sample was the blood of Suspect No 3.
Did Suspect No 3 do the crime? To answer that, you also need to be sure that the sample came from the crime scene. You need to be sure that there was no other legitimate reason for the hair being at the crime scene.
If it was semen from a rape victim you could be sure that Suspect No 3 did the deed, but you would have to be sure there was no consent. That would be fairly easy in cases of complete strangers.
The big trouble with DNA evidence is that juries can get so entralled by the DNA technology that these other issues get sidelined. But there is no doubt about the integrity of the science being able to say that this sample came from this human being and no other (unless he has an identical twin).
Of equal importance is result that this sample did NOT come from Suspects 1, 2, 4, 5, 6, and 7. This enables the police to concentrate their efforts elsewhere. And all too often police concentrate so much on a suspect who they think is guilty but who in fact is innocent that the trail goes cold. Police often concentrate on people with criminal records, too. If the database contains everyone upon conviction, DNA testing will quickly exonerate the innocent who might otherwise get convicted.
DNA testing is similar to ordinary fingerprinting (now 105 years old) in that fingerprints are unique. But many criminals do not leave fingerprints. They leave DNA more often – hair, skin, teeth, saliva and so on. Also DNA samples are faster to process and match.
This week the state and territory attorneys-general met to discuss DNA databases. (In Britain and the US they have just got on with it, with remarkable success.)
There are several questions:
From whom do you take DNA samples for the database? All suspects; anyone charged; everyone in jail; only those convicted of serious offences; the whole population, like the Australia Card?
How long to you keep the samples? Forever for everyone or only upon conviction?
At present Australian police forces have about 200,000 fingerprints on databases. The Federal Government wants these and DNA prints to be on one database with other information, called CrimTrac.
The British and US experience is instructive. Britain has about 250,000 DNA records on its database. They find that 40 per cent of crimes with DNA evidence now get solved. Rape suspects now plead guilty much more frequently.
In the US, DNA evidence exonerates suspects 30 per cent of the time.
In Australia, without a database, only 5 per cent of break and enter and car thefts are cleared up. Police hardly bother with them. And less than 50 per cent of sex assault cases result in a charge being laid. With DNA testing they will investigate more, catch more criminals and prevent further crime.
Further, if samples are taken from every crime scene and run through the database you will get matches against other crime scenes, even if you do not get your culprit.
Most of the crime is done by a very small percentage of the population. In Britain they estimate that 70 per cent of crime is done by 8 per cent of population.
Fairness of trial is important. But that is a case for widening the database. If the database is restricted to people charged or convicted, every time DNA evidence is introduced the jury would assume the person on trial had a criminal record and would be more likely to convict. Jury cases are rife with fears of prejudice, however. It would be easier to get rid of juries than protect them against scientific evidence that they might not understand or give too much weight to.
On privacy, the database contains only junk DNA – it does not tell anyone physical characteristics of the person from whom the same came. A name and address is kept in a separate but linked database. If there is a match against DNA at a crime scene, tests can always be redone to verify the database is accurate.
Bear in mind this technology has non-criminal applications. Just think this week if all the people missing in Switzerland had been on the database. Matches could have been made via computer in minutes and relatives spared a lot of agony.
The technology can also be used to pick up inherited disorders and is also useful in paternity actions. The DNA between one or two degrees (parent child, siblings, parent granchild) is similar enough to tell the degree apart but no so similar that you cannot tell they are different people. After the dirty war in Argentina, babies of people murdered by the military were kidnapped by barren military wives. Later grandparents used DNA technology to reclaim the granchildren and got custody. The Argentine courts ruled it was better to move the child now rather than allow them to come to the realisation in adulthood that they had been brought up by their parents’ murderers.
Justice is not only about protecting the accused; it is also about protecting future victims.