ABSTRACT
A policy decision will in most instances be already in place regarding which scientist or department will be involved in the various aspects of the casework. This will result in the correct exhibits being transmitted to the appropriate parties. A decision was made some years ago within the Forensic Science Service for discharge residue work to be done in specialized departments of the London and Birmingham laboratories not involved with routine firearms casework. This was done both to ensure the department did sufficient work so as to allow it to gain the necessary level of expertise, and also to reduce the possibility of contamination taking place. The London laboratory uses adhesive stubs for collecting possible residues from suspects and their clothing, chiefly to search for primergenerated residues, while the Birmingham laboratory uses swabs for both organic propellant residues and inorganic primer residues. Hand and face swabs or adhesive stubs are therefore sent to this unit along with control samples of discharge material from inside any spent cartridge cases recovered and clothing or vacuum samples taken from the clothing of persons suspected of involvement in the shooting incident. The police scene of crime officers are in turn supplied with swabbing kits and a comprehensive advice leaflet on their use. In the same way blood samples from the body and the scene can be sent to the biologists at the local regional laboratory in the area in which the shooting has taken place. Before firearms and ammunition are forwarded to the central unit involved in this work all fingerprinting work must be completed as it is unrealistic for the scientist to examine a weapon properly if fingerprinting is to be requested afterwards. Fingerprinting work is done either by the police or by a special dedicated forensic team situated in a central location who are equipped with all the latest equipment. It is important to bear in mind however, that current fingerprinting techniques may require the immersion of the weapon in hot dye baths, and in some instances there may be a requirement to strip the weapon to check for fingerprints on internal component parts. Such treatments can change the mechanical state of the firearm or even cause the loss of other potential findings. Again a decision must be arrived by way of consensus to determine the order in which certain tests are done, so as to ensure the needs of all parties are met.
