By CATHERINE MASTERS
Police forensic expert John Williams would love to be a fly on the cell walls on the day hundreds of murderers, rapists and violent offenders are told they must provide a DNA sample.
He and other top police have strong hunches that hardened criminals will be feeling uneasy about the Criminal Investigations (Bodily Samples) Amendment Bill, likely to be passed early next year.
The legislation will mean they will have no choice but to allow mouth swabs or blood testing, to provide DNA.
Convicted criminals can already be tested, but Justice Minister Phil Goff's bill will extend the 1996 legislation so that DNA from criminals jailed before then can be added to a national database.
The hope is that a range of unsolved cases will finally being laid to rest. The police also expect to solve a number of burglaries and other crimes by going to the High Court for permission to obtain compulsory samples from burglary suspects.
Mr Goff is certain there will be little opposition in Parliament, and expects the bill to become law within six to seven months, meaning that the DNA could be on the database in a year.
Police will not specify cases, partly so as not to raise false hopes among victims and their families, but they are sure there will be some big breakthroughs.
Examples from around the world suggest that at least some historic cases will be solved.
In Britain, the DNA national database already holds more than one million samples from suspects and the aim is that three million samples, representing around 5 per cent of the population, will be held by 2004.
The chance that a crime-scene sample will match a name already on the British database is around 40 per cent, because most crime is committed by a few people offending repeatedly.
The success rate for New Zealand's much smaller, but steadily growing, National DNA Database is similar.
Wayne Chisnall, forensic chief for the Institute of Environmental Science and Research (ESR), which manages it, says the figures show the power of the technology in linking crimes to individuals.
The database contains 22,000 profiles from people either convicted of crimes or who have volunteered their DNA for exclusion purposes.
The Criminal Sample Database has another 3984 profiles obtained from unsolved crimes.
DNA is found at 40 per cent of burglary scenes, and the database shows that in 30 per cent of cases, the offender was linked to another crime.
The law goes further in Britain, where police routinely take DNA samples from everyone brought into custody.
The Observer newspaper quotes the case of a man who raped a woman in 1991 and was jailed for the crime nine years later through a DNA test based on his theft of a bottle of whisky.
Surrey police report that they solved the 1968 murder of a 14-year-old boy. Exhibits including the boy's school blazer and satchel were re-examined and the killer, a suspect who was asked to provide DNA, was finally brought to justice.
Australia has CrimTrac, a system which includes a national DNA database and holds digital profiles of samples collected from convicted criminals. DNA helped lead to the conviction in July 1996 of the notorious New South Wales backpacker murderer, Ivan Milat.
In the United States, the technology has also freed death-row inmates wrongly convicted of murder.
Mr Goff says innocent people here are protected by a threshold.
"I'm not going to suddenly pounce on you in the street and say, 'Hey I want a sample and you have no choice'. That's overboard."
Police had to have reasonable cause to suspect someone of a crime and also had to persuade a High Court judge of the link.
Mr Williams, the general manager of New Zealand police forensic services, has already been contacted by officers digging out old files to see what kind of evidence they should be looking at.
In contrast to British policy, he is not aiming to get a certain percentage of the population on the database, although the general rule is the more samples the better.
It will take time and there will be no "DNA dump" on the stretched services of the ESR.
Sampling will be controlled and work prioritised.
"We haven't got the staff to dedicate to this in one hit. It will be planned and gradual so we can get the samples and get them through the system."
Mr Williams says targeting the right people is important and repeat offenders, such as recidivist burglars, are a number one target. He hopes that between 7000 and 8000 samples a year will be added.
West Auckland crime manager Detective Inspector Kevin Baker says DNA may hold the key to who murdered Marie Jamieson last year and left her naked body behind a Ranui factory.
Mass testing has already been carried out and more samples are being sought "from persons of interest".
It is possible that a DNA sample from a burglar could result in an arrest.
They are targeted for DNA testing not just because they break into homes and steal.
"It's been proved that you graduate from becoming burglars to becoming intruders into homes and then we end up in some cases with them becoming sexual assailants," Mr Baker says.
Detective Inspector Gavin Jones, crime manager for Auckland central, says officers will have to go through historical files case by case to see what physical evidence was collected.
He recently looked up a case he had worked on 30 years ago but did not find anything appropriate for DNA testing.
Mr Jones says a "hit" depends on a number of steps.
There must be a forensic sample in the first place. If there is, it must be able to be analysed for a DNA profile and then it remains to be seen if it matches an offender on the database.
On the DNA trail
Cases in which DNA evidence was vital:
* Travis Burns denied killing Whangaparaoa teacher Joanne McCarthy in 1998 but his DNA was found under her fingernails.
* Semen in murdered Papatoetoe woman Susan Burdett (1992) was found to belong to convicted serial rapist Malcolm Rewa in 1996.
* DNA helped to nail South Auckland serial rapist Joseph Thompson, who was jailed for 30 years.
Police will not say if the following historical crimes may be helped by DNA evidence, but the killers are among the country's most elusive:
* Jennifer Beard: The Welsh hitchhiker's body was found under a Haast River bridge in 1970.
* Alicia O'Reilly: The Auckland schoolgirl was murdered more than 20 years ago while her sister slept in the same room.
* Tracey Ann Patient: Her strangled body was found in the Waitakere Ranges in 1976.
* Olive Walker: The 18-year-old's body was dumped at a rest area south of Rotorua in 1970.
Police hope scientific advances or fresh leads will help to find the killers of:
* Parnell recluse Elizabeth Marusich, whose body was found in the Domain in 1995.
* Herne Bay woman Claire Hills, abducted and burned to death in her car on Mangere Mountain in 1998.
* Japanese tourist Kayo Matsuzawa, whose decaying corpse was found in a cupboard in the Centrecourt building in downtown Auckland.
* Marie Jamieson, who disappeared while walking along New North Rd, Kingsland, on February 10 last year.
By CATHERINE MASTERS