'Cold cases' will be re-opened by police; Breakthrough in DNA science leads to review.
THOUSANDS of "cold case" files on serious crimes are likely to be re-opened using a new DNA technique piloted in the North East.
Unsolved rapes and homicides are expected to be among the first cases reviewed under the technique made available to other police forces in England and Wales yesterday.
Forensic experts welcomed the move but said they could not comment on whether, if rolled out earlier, the method could have helped Sean Hodgson, from County Durham, who served 27 years in jail for a crime he did not commit, win an earlier release. The technology, called DNABoost, helps forensic scientists unscramble samples that contain mixed and muddled genetic fingerprints from more than one source.
Until now it has usually not been possible to identify a suspect whose DNA is mixed up with that of a number of other people. Three or four people may, for instance, have drunk from the same coffee cup or touched the same knife handle.
Previously in such cases, numerous and overlapping "spikes" in the DNA profile made it impossible to extract useful information from the evidence.
DNABoost, developed over the past three years by the Forensic Science Service (FSS), uses analytical software to disentangle the signals and produce a number of individual profile patterns.
Comparing these with records stored in the national DNA database may then yield a match to a potential suspect.
Experts believe the technique, a world first, could increase the number of provable cases by as much as 20% to 30%.
FSS scientific manager Martin Bill said: "We feel this approach is scientifically very sound and has low potential for false exclusion or inclusion.
"The take home message is there will be many thousands of cases, both moving forward and looking back, that will benefit from this technique. Our scientists are looking through the cold cases as we speak. We're hoping that some will come to light over the coming weeks."
Colleague Dr Mark Pearse said: "This is potentially a very significant breakthrough.
We could be looking at unsolved cases going back a considerable number of years."
The experts were not able to talk about specific cases, or comment on whether the technique could have helped Sean Hodgson, victim of one of the worst miscarriages of justice in British legal history, win his freedom earlier.
Hodgson spent 27 years in prison for a murder he did not commit until DNA evidence proved his innocence. He was freed last week after his conviction was quashed by the Appeal Court.
The launch of DNABoost today follows a successful trial involving South Yorkshire, West Yorkshire, Northumbria and Humberside police forces.
In every case where other evidence was used to verify its results, the technique was found to be 100% accurate, said Dr Pearse.
Each year the FSS looks at DNA evidence from around 100,000 cases.
About one tenth of these involve mixed or poor quality samples where DNABoost could be of help.
In practice the technique is most likely to be used as an intelligence gathering tool, targeting a suspect whose guilt may then proved with clinching other evidence.
It will also be used in conjunction with another technique introduced nine years ago called "low copy number" DNA profiling.
This allows very small amounts of DNA to be amplified to a point where a profile pattern can be seen. But the process itself can raise background "noise" which interferes with the result.
DNABoost will be able to unscramble confused data from low copy number profiling and allow investigators to make use of far more samples.