496:
In the interpretation of the results, Dr Clayton called on behalf of the appellant and Miss Groombridge, called on behalf of the prosecution disagreed to a limited extent.
Both agreed that Sheila Caffell could have contributed to this mixture of DNA but Miss Groombridge was prepared to go further and say that the findings provided support for the proposition that she had contributed to the mixture. She was, however, unable to determine the level of support provided.
In her evidence to the court she explained her reasoning. Seventeen of the twenty bands attributable to Sheila Caffell had been detected in DNA from the internal swabbings.
Random chance would have suggested thirteen common bands would be found and hence since there was significantly more than thirteen, it provided some support for the DNA of Sheila Caffell being in the moderator.
However, Miss Groombridge was unable to perform any sort of statistical evaluation of the likelihood of this happening and hence unable to assess the strength of the support.
Dr Clayton, whilst acknowledging the respect that he had for Miss Groombridge's views and whilst recognising the possible validity of the point that she made, felt that it was unsafe to draw any such conclusion.
Whilst we recognise that there may very well be merit in Miss Groombridge's evidence in this regard, we doubt very much whether a jury would have been prepared to place any significant reliance upon it so that it might have altered any view which they otherwise would have reached.
