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April 2016
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4.7.7.1 Handling of test items
For legal purposes, forensic units shall be able to demonstrate that the itemssamples examined and reported on were those submitted. A ‘chain of custody’ record shall be
maintained from the receipt of itemssamples which details each person who takes
possession of an item or alternatively the location of that item e.g. if in storage. Where exhibits are generated in the forensic unit e.g. fibre tape lifts, microscope
slides, a chain of custody record will be started and included in the case records. There shall be documented procedures which describe the measures taken to secure
exhibits in the process of being examined which are left unattended.
4.7.7.2 Assuring the quality of examination and test results
Analytical performance shall be monitored by operating quality control schemes that are appropriate to the type and frequency of examinationtesting undertaken by a
forensic unit. The range of quality control activities available include the use of:
reference collections; certified reference materials and internally generated reference materials;
statistical tables; positive and negative controls;
control charts; replicate examinationtesting;
alternative methods; repeat examinationtesting;
spiked samples, standard additions and internal standards; independent checks verification by other authorised personnel.
Depending on the particular test being performed, the forensic unit may make use of one or several of these examples to demonstrate that the test or examination is
‘under control’. The quality control procedures necessary in any particular area of work shall be determined by the forensic unit responsible for the work, based on best
professional practice. The procedures shall be documented and records shall be
KAN-G-19
Issue Number : 2
April 2016
Dokumen ini tidak dikendalikan jika diunduh Uncontrolled when downloaded
retained to show that all appropriate quality control QC measures have been taken, that all QC results are acceptable or, if not, that corrective action has been taken.
An effective means for a forensic unit to monitor its performance, both against its own requirements and against the performance of peers, is to take part in proficiency
testing programs. When participating in proficiency testing programs, the forensic unit’s own documented test procedures should be used. Performance in the
programs shall be reviewed regularly and where necessary, corrective action shall be
taken. Proficiency testing records should include: full details of the examinationstests undertaken;
results and conclusions obtained; an indication that performance has been reviewed;
details of the corrective action undertaken, where necessary.
4.8 Interpretation of the results of examinations and tests
