Innovative DNA techniques help to convict Voisey
The culmination of cutting-edge DNA technology developed by the Forensic Science Service (FSS) played a vital role in the conviction of Peter Voisey, sentenced last week to life imprisonment for the kidnap and sexual assault of a six-year-old girl.
The culmination of cutting-edge DNA technology developed by the Forensic Science Service (FSS) played a vital role in the conviction of Peter Voisey, sentenced last week to life imprisonment for the kidnap and sexual assault of a six-year-old girl.
Three types of DNA testing were used to obtain DNA profiles from complex evidence in the case, including the advanced techniques of Y-STR profiling and Low Copy Number (LCN) DNA.
The results, together with footwear mark analysis, helped to build up a `jigsaw` of evidence, linking Voisey to the crime.
The FSS`s Major Crime Specialist Advisor Peter Grant explained: Current DNA techniques initially only found the DNA of the victim. So the FSS used pioneering Y-STR testing to target the very small numbers of male DNA cells present amongst an overwhelming number of female cells.
This gave a partial DNA profile matching Voisey. The same technique was used on nail clippings, and gave a mixed DNA profile, again consistent with Voisey`s DNA being present.
The technique of DNA LCN was then used on minute traces of DNA from the victim`s skin, giving a mixed DNA profile, which both Voisey and the victim could have contributed to.
The final piece in the forensic puzzle came from shoe marks on the bathroom floor. The FSS found ten marks matching Voisey`s trainers, in terms of pattern, pattern size, and in some cases wear features.
Mr Grant added: A combination of traditional forensic science, footwear mark analysis and cutting-edge DNA technology were used together to build up a jigsaw of evidence linking Voisey to the crime.
The FSS is the market leader in the provision of forensic science services, offering a range of analysis and interpretation tools second to none, from footprints to forged signatures.
Voiseys conviction underlines the range of technologies that the FSS have recently produced.
Other developments include DNAboost, which can clarify a type of DNA sample that was previously uninterpretable. Another technique, pendulum list searching, interprets otherwise uninterruptible multiple DNA samples or mixtures.