Mr Green's tests though do have something more detailed for us. This is what he said about the bottle in his written statement:
Item RG.1 was a swab taken from the non bloodstained thread area of the Evian bottle (AMH.2). STR profiling of this swab gave an incomplete STR profile whose components were present in the corresponding positions in the profile of Dr Kelly so this DNA, presumably from saliva, could have come from him.
Item AMH.2 was a 500 ml clear plastic Evian water bottle. Airborne spots of blood and contact smears of blood were present on this item. STR profiling of one of the smears and one of the spots of blood gave full profiles, which matched that of Dr David Kelly. This shows that the bottle had been handled after Dr Kelly's wrist was injured.
The threaded top of the bottle and the inside thread of the Evian bottle top (AMH.3) were swabbed and the swabs combined. A full STR profile was obtained from the combined swabs, which matched the STR profile of Dr Kelly. This indicates that it was Dr Kelly that drank from the bottle.
The outside of the bottle top also bore faint smears of blood. STR profiling of one of these smears and of a separate non-bloodstained area was undertaken but no profiles were detected. Although it was not possible to determine from whom the blood originated it seems a reasonable assumption that the blood came from the same source as the blood on the bottle. If this is the case then it indicates that the top was taken off the bottle after Dr Kelly had injured his wrist.
Earlier in his report Mr Green explains that 'STR profiling is a sensitive DNA analysis technique'
The toxicologist (Dr Allan) records his analysis of the liquid in the bottle in his second report dated 18 August 2003:
The liquid consisted of 111 millilitres of clear colourless fluid with the appearance of water and having no unusual odour. The pH (acidity) was normal for water indicating that no corrosive material such as an acid or alkali was present.
Apart from a trace of dextropropoxyphene, nothing of else of significance was detected in the water.
Reading these forensic reports it seems as if the laboratory work has been thorough. Assuming all necessary care was taken to avoid for instance contamination of samples then I would have little reason not to accept the results. It is what is then inferred from these results that becomes critical.
For instance a trace of dextropropoxyphene (dp) was found in the bottle contents suggesting that dp was in Dr Kelly's saliva and thus he had swallowed some tablets. The most obvious conclusion of course but not necessarily true. A few drops of dp could have been added to the water by a "scene setter". Unlikely - yes. Impossible - no.
Again the DNA results from the STR profiling from swabs of the threaded part of the bottle and the threads in the bottle top suggest that Dr Kelly had drunk from the bottle. But at Harrowdown Hill? If it was an old Evian bottle with tap water in it then Dr Kelly might have drunk from it before leaving home. Very unlikely - perhaps. Impossible - no.
These are examples of instances where a forensic expert has to be incredibly careful about arriving at his conclusions. Where there is any reason for doubt then that doubt ought to be expressed.