A single flake of dandruff could be enough to link a suspect to a crime with new technology due to be used for the first time in the State Forensic Lab later this month. The PCR (polymerase chain reaction) method of profiling a DNA sample should allow scientists to come up with a DNA profile from a small amount of material, including a hair root, or a skin flake.
The technology, for which a double-walled room has been installed in the lab, should also allow for faster analysis. The PCR makes the sample grow and continue to grow until there is enough DNA to do analysis.
It takes about six weeks to come up with a DNA profile at the moment. With PCR this is reduced to three days. However, despite the technological advances and plans to set up a database for gardai, they are legally obliged to destroy DNA samples after six months.
Under the 1990 Criminal Justice (Forensic Evidence) Act, gardai have the power to take blood, urine, saliva and hair samples from a suspect in custody. Dental impressions, footprints and swabs can also be taken. However for blood, pubic hair, urine and saliva samples, consent must be given in writing by the suspect.
Most frustrating for forensic scientists is that the samples must be destroyed after six months. Britain keeps a DNA database. "When Britain put 100,000 people on their database they ran 35,000 crime stains through, everything from blood left in a car to semen stains in a rape. They found 7,500 men guilty as a result, some of serious offences," Dr Donovan says. "There is a considerable value in having a database."
"Our requirements are reasonably simple. We want to discourage people from committing offences. People usually start with small crimes, house-breakings etc. Nobody starts with the big stuff - the murders." One of the benefits of DNA evidence is that it can be used to eliminate suspects, Dr Donovan says. "In the Marilyn Rynn investigation we eliminated a large number of men as suspects. The alternative for a suspect is that gardai would have to spend time watching you and checking you out." The technology to profile a DNA strand is relatively new. It was first used by a British scientist in 1985 and patented by the multinational ICI. Until 1994 all samples were sent to Britain for testing before the technology was put in place in the State Lab.
A European Council Resolution in 1997 suggested that EU members consider "exchanging DNA analysis results. But it says this is not possible "until there are properly operating databases in Member States". A spokesman for the Department of Justice said there are no immediate plans to change the law to allow for the setting up of a database.
