Sample collection of wildlife forensic samples
General guidelines
Extreme care must be taken when collecting and storing samples to ensure the integrity of forensic material and downstream analysis. Contamination with other evidence during or after collection and poor storage of the sample may lead to degradation of DNA, compromising the analysis and end results. The following guidelines are provided to help ensure the integrity of forensic samples.
Latex or rubber disposable gloves should be worn during sampling to prevent the sampler from contaminating the evidence. Gloves should be changed between samples to prevent cross contamination.
Sampling should be performed with sampling kits containing sterilized equipment (knives, scalpels, tweezers, FTA cards etc. as appropriate) to prevent contamination of the evidence with other materials. Efforts should be made to avoid contamination with dirt, leaves and other debris.
DNA analyses require little tissue and in general a one inch cube of tissue is usually sufficient. Different sample types have different success rates when it comes to extraction and analysis of DNA, and collection of meat or muscle tissue is preferred. If this is not available, the following biological material may be submitted (in order of decreasing preference): hide or ear tips, liver or heart, blood, hair (with roots), and bone. As each particular crime scene varies in its exposure to environment and associated degradation and contamination of biological material, if at all possible a number of different materials should be collected.
Samples should be placed in a sterile container or plastic bag which is sealed with evidence tape or similar, and labeled with a unique sample identifier. Dried blood and other dried evidence should be stored at room temperature, in the dark. Tissue samples (wet, dry or frozen) should be stored at ‐20°C.
Each sample container (or bag) should be labeled using permanent marker with a unique identifier and other pertinent information (i.e. seizure tag number/sample identification number, date seized and date it came into your possession, your name and initials, paper seizure tag etc.). Please label the bag directly as labels and tape may fall off when frozen.
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Sampling of tissue (muscle, meat, liver, heart etc.)
DNA analyses requires little tissue and a one inch cube of tissue is usually sufficient. Fresh or frozen tissue should be stored frozen and shipped to the laboratory with ice packs. Dried tissue may be stored at room temperature and does not need to be shipped with ice packs.
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Sampling of blood
Wet blood should be collected by swabbing on an FTA card. The card should be dried before being sealed with a desiccant. Once dried on an FTA card, the sample is stable at room temperature and can be transported to the laboratory without ice packs. If it is not possible to swab the wet blood, then the bloodstained item (or a portion of the item, for large items) should be transported to the laboratory. These samples should be dried, if possible, and transported to the laboratory without icepacks.
If the blood is frozen, the bloodstained item (or a portion of the item, for large items) should be frozen and stored at ‐20°C until transported to the laboratory. These samples should be transported to the laboratory with icepacks
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Sampling of bone
Small fragments (at least 1 inch in length) should be collected ‘as is’ taking care to minimize contamination with soil or environment. Larger pieces of antler or skeletal bone are also acceptable. With the exception of bone/antler from a fresh kill site which should be frozen and transported to the laboratory with ice packs, bone should be dried and stored at room temperature. Dried bone does not require ice packs when transported to the laboratory.
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Sampling of hair
When sampling hair it is important that the root be collected intact. Thus hair should be plucked, not cut, from an animal or from hide. Moisture on the hair or root can result in DNA degredation and hair samples should be left to dry before being stored at room temperature. Hair samples do not need to be sent to the lab on ice.
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Sampling kits
• disposable gloves
• scalpels, tweezers, scissors
• FTA cards
• sterile swabs,
• zip‐type plastic bags
• permanent marker
• paper
If you require sampling kits or materials for sampling kits, please contact our laboratory. We can supply these materials at cost.
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Shipping
Once a sample has been taken it should be stored under lock and key to ensure the continuity of evidence and transferred to a forensic scientist at the RPC lab in Fredericton as soon as possible by delivering it personally or by bonded delivery service. Frozen samples should be shipped on ice packs in a leak‐proof container using an overnight courier service. Do not pack on loose ice.
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Questions about sampling?
Additional information on collection and sampling of wildlife evidence may be obtained by contacting one of our forensic scientists.
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