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In the age of CSI-style crime dramas it is difficult to imagine a time when DNA evidence wasn’t part of any criminal investigation.

But the first court case in New Zealand where DNA evidence was presented happened only as recently as 1990 and on the world stage, the first case involving DNA profiling went to court in the United Kingdom in 1986.

DNA can distinguish one individual from another. Photo credit: ESR

DNA can distinguish one individual from another. Photo credit: ESR

One of the scientists working at the time for the UK’s Forensic Science Services, and who was instrumental in developing the DNA profiling techniques that featured in that 1986 DNA profiling was built, is Dr Peter Gill, now a senior lecturer at Strathclyde University in Glasgow and a world-renowned expert in DNA forensics.

Dr Gill is in New Zealand this week visiting colleagues at Environmental Science and Research, the Crown research institute which does all of the New Zealand Police’s forensic work.

In this briefing at the Science Media Centre today, Dr Gill and ESR scientist Dr Sally Ann Harbison took journalists through the big scientific and legal developments of the past 20 years in the field of DNA forensics. The ESR booklet below is a good backgrounder to the New Zealand-specific developments.

Banking on DNA

One of the major developments in the evolution of DNA forensics both here and in the UK was the establishment in the mid nineties of DNA databanks that hold profiles of known criminals which can be compared against samples of DNA – usually blood, semen and saliva, taken from crime scenes. In fact New Zealand was the second country after the UK to set up a DNA Databank. Swabs are taken from crime scenes and analysed, then a DNA profile – a series of numbers that identifies a person’s unique DNA make-up, is created from the DNA material gathered and stored electronically in the DNA Databank.

Interestingly, the New Zealand DNA databank has over 120,000 DNA profiles in it, covering around two per cent of the population while the UK DNA databank formed around the same time has five million profiles, some 12 per cent of the UK population. Here’s some figures from ESR on the make-up of the DNA Databank and the success rate in matching profiles to crimes:

• over 105,000 DNA profiles from individuals
• over 23,000 DNA profiles from crime samples
• Link rates of 65% crime to person and 34% crime to crime
• Over 15, 000 links reported to date.

Despite the larger proportion of the UK population being covered by the UK DNA Databank, due to the UK police having wider powers to obtain DNA samples from suspects arrested for “recordable” offences, the crime to person link rate is higher in New Zealand than in the UK (somewhere around 53 – 55 per cent, I am told).

At an event at the Beehive tonight, when the Minister for Research, Science and Technology, Dr Wayne Mapp, enquired as to why this was, ESR scientists explained that the police generally have a good idea of who the criminals are anyway – and presumably have been able to obtain DNA samples from them along the way.

Nevertheless, the New Zealand Police from July will have wider powers,  under the Criminal Investigations (Bodily Samples) Amendment Act 2009 to take DNA samples from people who are charged with various offences. That could lead to more DNA profiles going into the DNA Databank.

Mission creep?

DNA Databanks exist around the world – the largest being in the US. Legislation governing who DNA samples can be taken from and when varies from country to country. Interestingly though, the UK’s DNA Database has become increasingly controversial as the number of DNA profiles of innocent people (those arrested on recordable offences but not prosecuted) rises to around one million of the five million DNA profiles on record.

Last week, one of Dr Gill’s colleagues who was integral to developing DNA forensics techniques, Sir Alec Jeffreys, voiced his criticism of the UK’s DNA Databank saying the profiles of innocent people should be removed from it:

‘Innocent people on the database are being used inefficiently to solve future crimes – and that goes against their civil rights.

‘If you took one million profiles off the database and replaced them with one million randomly selected profiles, would detections rise?’

Despite the concerns of critics, there’s no denying that storing DNA profiles so they can be compared with DNA taken from crime scenes has resulted in a lot of criminals being identified, cold cases being solved and innocent people being exonerated. As such then, the linking of DNA databases across borders would be increasingly useful for solving crimes as criminals become more  mobile. Dr Gill says such linkages are underway, particularly across EU countries and he envisages a sort of Google search engine for DNA databases that allows several DNA databases to be searched by law enforcement agencies in any one country.