1. To maintain the integrity of real evidence relied upon in court, it is necessary that the prosecution is in a position to account for all the time during which exhibits have been in the possession of the investigators. This includes the storage, custody, testing or examination and/or disposal or retention of the objects. You should refer to the section on Collecting Physical Evidence for further information and the relevant operational guidance, Material and evidence management (collection, retention and disposal). All stages in the chain of evidence should be accounted for by the person(s) concerned and given in a statement form.
2. To this end particular attention should be paid to the initial logging of the exhibit. It is clearly helpful if a unique reference is given upon receipt of any given exhibit, with that reference quoted at every activity undertaken with it, such as examination by experts or testing at a laboratory, so that it's history in the custody of the prosecution is one of transparent record. The court can thereby be sure of it's status at the time that the case is being dealt with.