Appeal against conviction for murder was allowed where the DNA evidence was presented to the jury in a misleading and inaccurate way and the judge failed to give a direction that evidence of a cell confession given by an untried prisoner should have been treated with caution.Appeal against conviction for murder. The appellant ('MP'), was convicted in Jamaica of murdering KD during the course or furtherance of rape. The Court of Appeal of Jamaica dismissed MP's application for leave to appeal. He appealed to the Privy Council. The prosecution case relied on: (i) a confession said to have been made in the presence of another prisoner, S, while MP was in custody, (ii) the results of DNA testing, and (iii) evidence of motive. MP challenged the DNA evidence and the alleged confession and criticised the judge's directions and interruptions by the judge when MP was giving evidence. The issues were :(a) whether the DNA evidence was misleading and inaccurate; (b) whether S's evidence about the alleged cell confession was of such character as to require the judge to draw the jury's attention to the possibility that it was tainted; (c) whether the judge's directions and interruptions were wrong and prejudicial; (d) whether a reasonable jury properly directed would be bound to convict on the admissible evidence; and (e) whether there should be a retrial.HELD: (1) The Crown accepted that the DNA evidence misled the jury. The product of the DNA tests done in this case were sufficient to provide support for the Crown's case but it was not accurately and fairly presented to the jury. The expert witness stated that spermatozoa from a vaginal swab from the deceased came from MP, but that conclusion was fallacious. That fallacy was known as "the prosecutor's fallacy" (see R v Doheny (1997) 1 Cr App R 369). The fact that the marker test showed that the male fraction in the vaginal swab matched MP's samples was not probative in the absence of other evidence. The probative effect of DNA evidence depended on whether there was some other evidence which could demonstrate its significance and it was for the jury, not the person who gave the DNA evidence, to assess its significance in the light of that other evidence. It was within the province of the expert to say what was the statistical likelihood of the same sections or bands of DNA being found in the male fraction of the swab as was found in MP's sample. But it was not for her to express an opinion as to the probability that it was MP's spermatozoa which were found in the deceased's vagina. Further the effect of her evidence was greatly to exaggerate the random occurrence ratio. There were sufficient inaccuracies in the DNA evidence and the judge's summing up about it for the jury to have been seriously misled as to the likelihood that it was MP who murdered KD. On that ground the conviction was unsafe. (2) The jury ought to have been told by the judge that they should take special care when they were considering S's evidence. He should have drawn attention to the factors which might indicate that the witness had an improper motive which tainted his evidence. Those were that S was an untried prisoner, that it was not unknown for persons in his position to wish to ingratiate themselves with the police and that to give them information that MP had confessed to the crime for which he was being held was a convenient and obvious way of doing so. In the absence of an express direction to treat S's evidence with caution, MP did not receive a fair trial. On that ground too MP's conviction was unsafe. (3) It was not necessary to consider the other grounds of appeal. (4) It could not be said that a reasonable jury would inevitably have convicted if they had not been misled about the DNA evidence and had been properly directed in relation to S's evidence. (5) The case was remitted to the Court of Appeal of Jamaica to decide whether there should be a retrial.Appeal allowed.

[2003] UKPC 9