It took police less than a week to arrest a man in connection with the brutal attack and rape of a woman in Nelson on New Year's Day after his DNA allegedly matched evidence at the scene, but one academic says developing the techniques to catch the criminals takes time.
The 62-year-old woman was bashed and sexually assaulted in a community garden in the Victory area of Nelson as she worked alone, in an attack police described as "cowardly and prolonged''.
Police arrested Nelson man Hilton Hone Heke, 22, yesterday. He had already been on the police suspect list before he was linked, allegedly by his DNA, to the crime.
University of Otago Associate Professor Jurian Hoogewerff, who is director of the University's Forensic Analytical Science Program, said forensic testing did not happen as quickly as people saw on television.
"Developing the techniques takes time. It takes one, two, three years to develop a method.''
New Zealand had one of the top forensic testing institutes in the world, he said.
"It's state of the art what people do down here.''
Most techniques developed here and abroad were being used, but police budget constraints restricted when and if various processes were used.
Major cases often had unlimited resources, but "there is always budget consideration''.
Because New Zealand was a relatively small community, cases often got solved, he said.
The Police Annual Report for 2011/2012 said there was 22,757 DNA profiles stored on the DNA profile databank.
On 342 occasions in 2011/2012 a DNA profile which had been obtained from evidence at the scene was matched with a DNA profile obtained from a suspect.
And on 1134 occasions a DNA profile obtained from evidence at a crime scene matched a DNA profile on the databank.
A team at Environmental Science and Research (ESR) is currently working on revolutionising forensic work at crime scenes.
The Future Crime Scene Project is developing and testing new technologies to help solve crimes more quickly and give jurors detailed 3D tours of crime scenes.
Forensic development manager Bjorn Sutherland told the Herald late last year that technology was enabling ESR to develop forensic science in ways that have not been possible until now.
ESR science leader Dion Sheppard said the work the Wellington ESR laboratory was doing - looking at technology that had traditionally been lab-bound with the intention of taking it to the field - would mean faster information flow to investigators, making it "less likely the trail would go cold''.
In December last year Charles Wilson Bullen was sentenced to community work and supervision after admitting tagging a swastika and lewd pictures of body parts on a visiting Australian Air Force plane before spitting on it in September 2008.
He was caught after a droplet of his spit, found by police at the Whenuapai Airbase in west Auckland, matched a DNA sample from the 35-year-old professional painter, linking him to the scene.