Tiny samples of DNA evidence are safe to use in criminal prosecutions, in spite of recent concern from the police and the judiciary that the technique is flawed, the forensic science regulator has ruled.
Andrew Rennison was responding to an independent report by scientists at the University of Strathclyde into the analysis of low-template DNA - amounts too small for standard DNA profiling. The report found the technique to be scientifically sound and Professor Brian Caddy, who carried out the review, said it should not cause wrongful convictions.
The review comes after last December's verdict in the Omagh bombing case where Sean Hoey, a republican, was acquitted of killing 29 people in 1998. The British-pioneered low-copy DNA technique of amplifying small amounts of genetic material so it can be read was used in the prosecution case and in his verdict Mr Justice Weir, the trial judge, said he was not satisfied that it was valid for use as evidence. He said that in the Omagh case the DNA material had been so amateurishly collected and stored as to be valueless. He also questioned the level of academic analysis of the technique.
Low-template DNA is also known as "touch DNA" because investigators can extract samples from just four or five cells deposited by suspects only briefly holding objects such as a gun, a door handle or a glass. The technique was used in the Peter Falconio murder trial in Australia as well as the conviction of the rapist Antoni Imiela, who struck several times in south-east England.
If the review had found problems with the science it could have triggered the re-examination of scores of criminal cases.
However, the review's authors called for improvements in the collection of DNA from crime scenes and in its analysis, to avoid the evidence becoming unusable.
Caddy made 21 recommendations to standardise procedures , including ensuring that police evidence-gathering kits are "DNA-clean", to avoid contamination with someone else's genetic profile, a national agreement on how to interpret the results from low-template DNA, and clear guidance on how courts should interpret the evidence. The report's authors also voiced concern at the quality of forensic science conducted by police laboratories, which often analyse low-template DNA first. "I am satisfied the science is very safe," said Rennison. "However, there is clearly work to be done to develop a coherent standards framework that is transparent, accessible and used across all the facets of forensic science."
The Association of Chief Police Officers in England and Wales recommended that chief constables suspend its use in criminal investigations while a review was carried out by the Crown Prosecution Service.
The CPS review concluded that "low-copy number DNA analysis provided by the Forensic Science Service should remain as potentially admissible evidence".
