Forensic science feature: from the textbooks to the courts
Tuesday, 13 August, 2002
While forensic scientists used to use blood typing and other methods to identify crime suspects, DNA identification and profiling is now the method of choice. Since its first use in an Australian court in 1989, the technology has moved from the controversial to the mainstream, although controversy still rages around the issue of creating databases of DNA profiles for criminal identification.
"It came from the textbooks to the courts in just a few years," says Prof Claude Roux, head of the Forensic Science program at the University of Technology Sydney (UTS). DNA profiling these days is a PCR-based technique that uses highly variable regions known as short tandem repeats (STRs) to construct a profile of an individual's DNA. Although there are several combinations of STRs used, Australia's forensic community uses Applied Biosystems' AmpFLSTR Profiler Plus PCR amplification kit, which contains nine STRs plus Amelogenin, a marker found in slightly different versions on both the X and Y chromosome used to determine gender.
Other countries use similar systems, with a variety of kits available from Applied Biosystems and Promega, the two major suppliers of DNA profiling and genetic identity testing technology. The technique is sensitive enough to discriminate between any two individuals in Australia except identical twins, says Dr Roland van Oorschot, forensic scientist and manager of R&D at the Victorian Forensic Science Centre (VFSC). The possibility of two profiles matching is usually one in multiple billions. "It obviously has become more important evidence, the likelihood of two samples being the same," van Oorschot says. He notes that most of the time, DNA is used to exclude suspects.
Another technique used occasionally, particularly when very degraded DNA is present, is mitochondrial DNA typing, where a variable region of mitochondrial DNA is examined. Mitochondrial DNA is inherited maternally and there may be thousands of copies in a single cell. This method is primarily used for missing persons and to identify unknown remains. But van Oorschot says that there are new methods on the horizon taking advantage of the flood of information and new technology coming from genomics research, such as the use of SNPs (single nucleotide polymorphisms), microarrays and robotics.
"SNPs might be beneficial in certain applications in forensics, for example when DNA is very degraded," he says. But van Oorschot concedes that the standardised use of the STR-based Profiler Plus system for the national DNA database might hold back the implementation of new SNP technology for criminal identification.
However, linking criminals to evidence is not the only way that new DNA technology can be used. SNPs might become relevant in other parts of the investigative process, such as building up a physical picture of the suspect based on their genes. Phenotyping is a hot topic in forensic science circles, and that's not surprising. In a case where the only evidence left behind by a perpetrator is a trace of DNA, the ability to describe the suspect, at least in terms of hair colour, eye colour, skin colour, and even characteristics like a strong jaw or a cleft chin would provide the police with another way to identify potential suspects in the absence of an eyewitness, although it is unlikely to be used as evidence in court.
The UK's Forensic Science Service is investing heavily in research on phenotyping and has already come up with tests for mutations in the gene that is responsible for red hair in its recessive form. And DNAPrint, a company in Florida in the USA, has developed a test for determining eye colour, and is now working on hair colour as well. "That will be an important advance, limiting testing of suspects to the most likely," says Dr Paul Roffey, a forensic scientist based at Charles Sturt University in NSW, who has done some research in the area in the past. He speculates that forensic scientists will even be able to estimate approximate age via the length of the telomeres.
But it is likely to be a while before phenotyping is used in forensic science routinely. "These things need to be researched very thoroughly and implemented very carefully," warns Simon Walsh, a forensics PhD student at UTS. "Because of the nature of forensic science it lags behind the cutting edge."
According to van Oorschot, one area where Australia is at the forefront is in collecting and typing trace amounts of DNA. Although 1 nanogram is the standard amount required for DNA profiling, he claims that profiles can be obtained using significantly less. While blood, saliva and semen are still the main sources of DNA for forensic testing, trace amounts of DNA can now be obtained from touched objects, such as the handle of a weapon, the steering wheel of a stolen car and the inside of a glove, van Oorschot explains.
The big drawback with many forensic techniques, including DNA testing, is the need for a lab in which to do the testing. One subject that gets many forensic scientists excited is the prospect of miniaturisation and portability of testing equipment.
"There's a lot of emphasis on miniaturisation and taking the lab to the field," says Alistair Ross, Director of the National Institute of Forensic Science (NIFS). He says that microfluidics and lab-on-a-chip technology are sparking interest among forensic scientists. "There will be a shift of analysis out of the lab and into the field. The crime scene officer will be able to get information on possible suspects at the scene," says Roffey.
Human DNA is not the only DNA of interest in forensics. Roffey is developing DNA tests that can discriminate and identify DNA from a wide range of species. His major focus is on abalone, which is a poaching target in Australian waters, but Roffey says that there is a wide range of applications for tests like these. "The tests I'm developing don't just work on abalone, they work on species from humans down to flies and slugs," he explains.
But research funds for forensic science are difficult to come by. NIFS coordinates education, training research and information exchange for forensics organisations around Australia, but its current research budget is only around $100,000 per year, not nearly enough to support an innovative research program. The funding that comes in for forensic research from other funding bodies like the Australian Research Council is also low and must compete with all other fields of science.
NIFS' Alistair Ross would like to see more research to enhance forensic science capabilities in Australia. Last year his organisation put together an innovation strategy, seeking a $4-5 million annual operating budget from the government. "One of the reasons we thought it was time to develop a national strategy for research is that there are now 18 universities in Australia offering forensics units," explains Ross.
Bogged in casework
Most Australian forensic research is performed by Honours, Masters and PhD students in programs like these, says Ross, partly because forensic scientists are so bogged with casework they don't have time to do research as well. According to Ross, the proposed Forensic Science Innovation Strategy suggests a decentralised national centre for research with nodes in every state, similar to a CRC, but with broader focus and more for the public good than for commercial benefit.
NIFS' strategy would encompass three directions of research, including adoption of forensic technology for use in Australia, extending research from mainstream science to use in forensic science and developing innovative solutions to forensic problems. "Unfortunately in Australia we don't have a lot of research in the forensic area in biotechnology," Ross says.
Questions over DNA databases
The development of national databases for DNA profiles is a controversial topic. In Australia, each state has its own database, and the National Criminal Investigation DNA Database is in the process of being set up under the auspices of CrimTrac.
The first national DNA database was set up in the United Kingdom in 1995, and now holds DNA profiles from over one million suspects and convicted criminals. According to the Forensic Science Service, 100,000 crime scene samples have been matched to suspects and over 10,000 crime scene samples have been linked to other crime scenes using the database.
New Zealand and the US also have national DNA profiling databases in place. Simon Walsh, a PhD student at the University of Technology in Sydney, is studying the effectiveness of DNA profiling on criminal justice outcomes. "New legislation has given the police much greater powers to take samples for testing. This has all happened without anyone looking at an empirical analysis of how successful DNA profiling has been," he says.
Walsh hopes to develop a predictive mathematical model of the DNA profiling system. He believes that it is important that it comes from the forensic community. "Politicians, forensic scientists and police tend to be advocates of DNA profiling but tend to use anecdotal evidence if how well it works. If we are able to successfully model it, we will get some data to contribute to the debate," he said. "Personally I think it's a fantastic piece of technology with respect to the criminal justice system, but it needs to be used judiciously."
The Australian Law Reform Commission has been studying the issue of genetic privacy, and the protection of human genetic information and is due to release a discussion paper later this month, which will include a section on DNA profiling and law enforcement. Although details of the discussion paper are not yet available, some of the questions considered in the inquiry include issues of consent, how long samples should be stored and how they should be analysed, destruction and de-identification of samples and profiles, and sharing of information between jurisdictions as well as the possible need for independent oversight of the database. There have also been a number of other inquiries into the issue of DNA profiling in Australia at the state level and independently.
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