Crime Scene Collection Techniques

The importance of avoiding cross contamination cannot be overemphasized. The crime scene clean up investigator performing the collection must ensure tools are clean or sterilized and that gloves are changed between handling each sample.Collection methods differ depending on the type of evidence and the substrate upon which it is found. It is preferable to collect evidence in its original state. If the evidence is fragile or can easily be lost, the entire object should be collected and packaged, if size and circumstances permit.Some laboratories recommend the submission of substrate controls. Substrate controls are clean samples of the collection materials or unstained portions of the material the biological evidence is deposited on. The laboratories can use these to troubleshoot contamination, Polymerase Chain Reaction (PCR) inhibition, or interference with fluorescence.The investigator should consult the local forensic laboratory and refer to the department standard operating procedures regarding collection and preservation of biological evidence.