The SOP (Standard Operating Procedure) for collecting drug evidence in a crime scene is essential to ensure that the material that is to be collected does not become contaminated. If it does, the entire investigation may be thrown off as a result of a false-negative or a false-positive test. Hence, the collection is the most important part of the investigation.
First, the CSI has to wear protective gear not only to prevent his or her own body chemicals to affect the drug, but as a standard procedure for protection. Each piece of evidence must be collected in separate HAZMAT bags and identified by case number.
The Louisiana Police Crime Lab states the following requirements when putting any evidence in bags:
- the collecting person's initials
- the date and time it was collected
- a complete description of the evidence and where it was found
- the investigating agency's name and their file number
The HAZMAT bags must be weather-proof or at least have heat control. It is a well-known fact that acidic drugs as well as pills, liquids, and solid drugs like crack-cocaine are quite reactive to heat.
According to the Louisiana Police Crime Laboratory online,
UNDER NO CIRCUMSTANCES SHOULD EVIDENCE CONTAINING MOISTURE BE PACKAGED IN PLASTIC OR PAPER CONTAINERS FOR MORE THAN TWO HOURS. Moisture allows the growth of microorganisms which can destroy or alter evidence.
Therefore the crime scene investigator must use their best judgement to identify the condition in which the drug is found in order to determine the proper storage and containing.
The storage of the substances must also be weather-controlled and there has to be special consideration given to taking pictures of each piece of evidence, make inventory, and compare it to the evidence that actually made it to the lab.