Hi markiemarkie said:Softus what about a D,N,A conviction ? if some one who's d,n,a match's up with a little girl who's been you know what, then murdered. then there is no argument if he/she did or not do it. yes or no ? if you state yes, then why do you write ( it is not possible to convict a murder beyond all doubt ) ps i know what your responce is going to be
A reasonable question, to which I have an answer, although if you know it already then it seems a bit superfluous
Firstly, DNA evidence. There is no such thing as a "match up" using a DNA sample. Whilst the national database is in the throes of an upgrade in the accuracy of the profiling process, and the attendant accuracy of the resultant measurement, is it not possible, nor has it ever been possible, to say that any given sample is from a particular individual.
The way that DNA evidence is presented in court has been the subject of revision and refinement since the early days when it was falsely known as "DNA fingerprinting". The extraction and measurement of the DNA strands performed by the Forensic Science Service is a skilled and relative measurement against a control sample. The correct way to describe the evidence is to express it arithmetically as the frequency of the occurrence of a particular set of DNA strands in the general population. Hence the measurement yields a likelihood that a particular suspect's DNA, if it's sufficiently similar, would be found in an otherwise randomly selected member of the population.
This is why there is always an argument (aka trial) to determine whether or not a given suspect is guilty, hence DNA evidence cannot be used to convict without other evidence.
Therefore it is not possible to secure a conviction that is beyond all doubt.