Global DNA search a step closer, says expert

Twenty years after DNA evidence was first used in a New Zealand court, a "Google" search of profiles that could allow investigators to track suspects globally is developing, one expert says.

British researcher Peter Gill - in New Zealand to work with Environmental Science and Research DNA forensics experts - said a single global bank of DNA was unlikely, but that police would one day be able to search all countries' databases.

"It is going to develop more like a Google search engine of all the national DNA databases throughout Europe or across the rest of the world ... more like a virtual database," he said.

"It is happening in Europe now, for example a DNA profile which is downloaded in Germany will automatically search the Austrian database."

New Zealand police - who hold the DNA records of about 100,000 people - will have wider powers to take DNA samples under the Criminal Investigations (Bodily Samples) Amendment Bill.

From 2011, police may take DNA samples from anyone they intend charging with an imprisonable offence.

The samples will be included in the DNA databank for possible use in DNA profiling.

Dr Gill said some cross-checking between countries was already routine. "If there was a crime committed in New Zealand, and it was suspected a UK citizen was responsible, it would be possible to compare that DNA profile with the UK DNA database."

"You have to take account of national legislation and that means in one country [for example] only people who have committed a certain crime would be allowed to be on this global database. So there will be a number of filters," he said.

New Zealand's first DNA conviction, in 1990, was that of Michael James Pengelly, for the murder of an elderly Auckland woman.

Since then its use has become widespread and its techniques made popular in crime shows such as television's CSI franchise.

Asked if CSI had helped juries understand DNA evidence, Dr Gill said it had done the opposite. Instead, it had created a wrong perception that if someone's DNA was found on the scene they must be guilty, he said.

ESR's Dr Sally Ann Harbison said the "CSI-effect" had created unrealistic expectations about what forensic scientists could do.

In other developments, Dr Gill said scientists were working hard to link physical characteristics such as hair, skin and eye colour to DNA markers - possibly giving police a partial description of someone whose DNA was found at a crime scene.

They had made progress with a DNA marker for red hair but it was only about 80 per cent accurate, he said.