Blood on their hands

By ALICE SHOPLAND

Trying to extract DNA from human bones which had spent up to 10 days in the stomachs of salt water crocodiles was the challenge forensic scientist Simon Walsh set himself for his honours degree at the University of Queensland - equivalent to a master's degree in this country.

The crocs have fearsome digestive acids to compensate for the fact that they don't chew their food. The aim of Walsh's research was to make identification of croc victims possible for up to 10 days after consumption.

That was in 1994. These days Walsh, 29, works at a safe distance from crocodiles. He heads the Crime Sample Database Unit (CSDU) at ESR, the Institute of Environmental Science and Research, in Mt Albert.

The unit's role is to analyse the DNA content of biological samples such as blood, semen, hair and saliva, the vast majority of which are collected at crime scenes by the police. This is the only lab in New Zealand to analyse DNA.

Walsh says the occasional private individual comes to the unit with a biological sample they want analysed - the underpants of a suspected cheating wife, for example - but ethical and legal sensitivies mean that few of these go ahead, even if the person is willing to pay the several thousand dollars required.

Potential evidence - including paint, glass, fibres, tyre prints and ballistics, as well as the biological samples - is collected at the crime scene by scientists and technicians from the ESR's central laboratory and distributed to the relevant units for analysis.

If a blood-stained garment was found at the crime scene or in the possession of a suspect, for example, one of the blood stains would be cut out and handed over to CSDU.

Each sample takes seven or eight working days to go through the various processes involved in DNA analysis.

Each scientist works with a technician, and together they work on between 100 and 150 cases a year, usually in batches of up to 30. About 10 to 15 per cent of cases require the scientist to present their findings in court.

While many of the biological samples are compared with a sample from a suspect, junior scientist Delia Moss specialises in processing no-suspect crime samples alongside Walsh at ESR. These are compared with the approximately 17,500 samples on the National DNA Database, and a possible match is found almost four times in 10.

Moss, now 27, studied molecular biology at Canterbury University and applied for a technician's position at ESR in 1998 when she returned from her OE. A year ago she was promoted to scientist.

She says she was initially disappointed that the job wasn't in the service centre, whose scientists and technicians visit crime scenes and inspire films, television programmes and crime fiction.

"But now I know that most of their time is actually spent in the lab, not at the scene, and their lab work isn't as interesting as ours."

Moss says that she enjoys the work because it's so closely related to real life, unlike many careers in science.

"A lot of the cases are burglaries, and I like feeling that I can help people who've been affected by that. And if we can help to slow the progress of some criminals, that's great too."

Moss is doing her Master of Science degree part-time - she says the flexible working hours at ESR are a major bonus - and is currently working on the research component. She's working with heat-tolerant enzymes sourced from Rotorua and Mt Erebus.

"The idea is that heat makes many chemical processes work better and faster, so I want to see if these enzymes [which are similar to those usually used in DNA analysis] can be used to extract DNA better or more efficiently."

As well as laboratory positions for technicians and scientists, there are other careers in forensics, including document examination, photography, botany, entomology, pathology, toxicology, psychology and criminal profiling.

These specialists are often based at institutions like universities, rather than labs like ESR. Walsh says most sciences have a degree of forensic application, and most countries now have specialist post-graduate qualifications in forensic science.

* To get into forensics you'll almost certainly need a Bachelor of Science degree. Post-graduate studies in forensic science are offered at the University of Auckland. For further information, visit KiwiCareers and Forensic Science Society.