DNA profiling: evidence for the prosecution

Abstract

In giving a prosecutor's perspective on the use of DNA profiling in criminal proceedings, my aim is to put the use of DNA profiling in context alongside other scientific evidence, to show how DNA profile evidence is in fact used in the courts, and the value of that evidence. I hope to be able to illustrate that this type of evidence is most often used in court as part of a body of scientific evidence linking an accused with a of a fingerprint in blood found in the kitchen sink. The accused was convicted, and on appeal the High Court held that in the absence of any explanation for the presence of the fingerprint, the jury were entitled to hold that it was made by the murderer when cleaning up after the murder. The accused's failure to refute the expert evidence in this case entitled the jury to convict. particular crime, and is only very rarely presented as These cases can be contrasted with the case of Reilly v the main evidence on which a prosecution relies. H M A [3] in which the fingerprint of the accused was Any evidence which links an accused to the locus or to found on the back of a false number plate of a car the victim of a crime will be of value to a prosecutor used in an attempted robbery, the car having been faced with the task of proving an accused's stolen the day before. A jury convicted the accused, involvement in the commission of that crime. but on appeal the High Court held that the possibility The prosecutor has to prove two essential facts: that existed that the fingerprint had been put there at an the crime has been committed, and that the person earlier stage. This meant that the jury was speculating as to the accused's actual involvement in the robbery, who committed the crime was the accused. The accused must be associated with the crime by evidence and the conviction was therefore unsafe, and was quashed. from at least two sources. An accused may be sufficiently identified by circumstantial evidence consisting of corroborated expert evidence of a scientific nature linking the subject of the evidence to the commission of the crime and identifying the accused as the person to whom the evidence relates.