The prosecution case against JB at trial included a lack of gunshot residue on SC's hands. This also featured at JB's 2002 CoA hearing insofar as the defence claimed the correct procedures were not followed for evidence gathering and handling.
Perhaps a lack of gunshot residue can be explained by forensics?
"A rifle or shotgun may not deposit GSR on hands, but more likely in the crook of the support arm". (Dalby et al, 2010)
"A rapid loss in numbers of GSR particles occurs from 1 to 3 hours post firearm discharge, though maximum recovery times of 1 to 48 hours have been reported". (Dalby et al, 2010)
http://library.med.utah.edu/WebPath/TUTORIAL/GUNS/GUNGSR.htmlThe absence of GSR does not indicate innocence.
"There are factors that contribute to particulate loss that must also be taken into consideration. For instance, suppose a firearm is discharged in a static environment (no wind or airflow). Hand samples are then collected immediately after the discharge on clean, dry hands. It would not be unusual to detect hundreds to thousands of GSR particles on these samples. Alternately, suppose a firearm was discharged outside during a windy day with inclement weather.
Samples are collected several hours after the discharge, giving the subjects ample time to move, shake off, wipe, or wash their hands. In this instance, it might not be possible to find any GSR particles on the samples. This absence of gunshot residue is not an indication that the subject is innocent of discharging a firearm. All factors concerning particulate loss must be taken into account when determining if results are consistent with the aspects of a specific scenario".
http://www.forensicmag.com/articles/2012/09/science-behind-gsr-separating-fact-fictionDI Cook moved SC's hand. Trial transcript:
Q: It would appear that the hand and arm have been moved who was responsible for that? A: I was sir.
Q: For what purpose? A: To demonstrate the blood marks which were not readily visible under the wrist.
http://miscarriageofjustice.co/index.php?action=dlattach;topic=168.0;attach=297