What is the ideal way to preserve biological evidence?
Solution: Always package biological evidence in paper, especially for long-term storage. If plastic must be used temporarily in court, always return to paper for further storage.
Photograph and document the scene. Collect trace materials (especially from probable points of entry) Collect low-level DNA evidence by swabbing areas of likely contact. Collect other items that may contain biological evidence.
Long-Term Storage Equipment for Biological Evidence
In many jurisdictions, however, biological evidence must be preserved on site. Many police departments have refrigerated compartments installed along with other temporary evidence lockers.
Formaldehyde (HCHO) in the form of formalin (40% solution of formaldehyde) is used for preserving biological specimens.
Each biological specimen should be packaged ac- cording to established forensic practices. Once the samples have been collected, they should be promptly delivered to the forensic laboratory. To min- imize specimen deterioration, items should be stored in a cool, dry environment until they are submitted for testing.
The area containing the sample to be collected should be marked so that the area can be related back to the item collected. 2. Always wear gloves and a mask when collecting any form of biological evidence. Put on a clean pair of gloves when handling particularly small biological samples before collection.
Place small glass fragments in paper bindles, then in coin envelopes, pill boxes, or film cans which can be marked and completely sealed. Place large glass fragments in boxes. Separate individual pieces with cotton or tissue to prevent breakage and damaged edges during shipment. Seal and mark the box containing them.
In cases where a suspect has not yet been identified, biological evidence from the crime scene can be analyzed and compared to offender profiles in DNA databases to help identify the perpetrator. Crime scene evidence can also be linked to other crime scenes through the use of DNA databases.
DNA has been the predominant information storage medium for biology and holds great promise as a next-generation high-density data medium in the digital era. Currently, the vast majority of DNA-based data storage approaches rely on in vitro DNA synthesis.
Evidence that is wet or that may contain body fluids (blood, semen, etc.) must be air-dried completely. Such items should be packaged in paper bags/boxes. Known samples can be collected by rubbing sterile swabs against the cheek, inside the mouth.
Should biological evidence be stored in breathable containers?
Biological: When collecting evidence for DNA analysis, it's best to store biological materials in breathable storage containers. These containers prevent condensation, which can lead to mold and bacteria growth that can compromise the quality of samples.
Additionally, biological material can be a source of DNA which can allow an individual to be linked to a scene and a specific biological sample. DNA can be obtained from a variety of sources including blood, skin cells, semen, hair, saliva and tissue. Certain types of DNA evidence are more probative than others.
Biological Evidence means evidence that is recovered from a crime scene, including but not limited to blood, saliva, sperm, hair, tissue, bones, teeth, or other bodily fluids 193.
Biological Evidence. Identification of additional characteristics that could further differentiate blood. 1937 - Rh factor determined. More than 100 blood factors determined to date. A-B-O most important for medical use.
Formalin (formaldehyde gas dissolved in water) is the most widely used, economical, and effective preservative. Used in low concentration (5%) it effectively preserves the entire specimen and prevents decay.
Transportation and Storage
In addition, they should be aware that direct sunlight and warmer conditions may degrade DNA, and avoid storing evidence in places that may get hot, such as the trunk of the police car. To best preserve DNA evidence, store in a cold environment.
The specimen are generally preserved at 4oC during the time until they are analysed. For long term storage it has to be kept in freezer (- 10oC) until analysed and disposed off. The most commonly used preservative for viscera tissues are saturated solution of common salt.