Delivery of evidence
The evidence collected from the scene should be properly packaged, labeled and sealed before it is delivered to the laboratory for testing. Proper labeling is essential for laboratory applications as well as for court usage. All the items to be submitted to the laboratory should have the name or the names of the suspects or victims, a brief description of the contents of the package, the location the item was collected, the investigator's name and the date and time the items were collected. It is also imperative to place different items in different packages to avoid cross contamination. The packaging containers should be properly selected according to the items to be packaged. Sealing the outer packages of the evidence helps in maintaining the quality of evidence and ensures that the evidence is not tampered with while being delivered to the laboratory. It is also significant to take into consideration safety issues while packaging the evidence. Where the contents of the packages contain items that are likely to be hazardous it is critical to label such packages appropriately to avoid harm.
How to test blood evidence
There are three types of tests that can be conducted on blood evidence. The first test is the conventional serological tests which analyses proteins, antigens and enzymes present in the blood samples. The elements tested here are vulnerable to degradation and requires large samples to obtain ideal results. The other test is the restriction fragment length polymorphism, which analyses the presence of certain DNA sequences in the white blood cells. DNA does not degrade rapidly like proteins and enzymes and, therefore, this procedure is less likely to be affected by degradation. The third type of test is the polymerase chain reaction test. This test assists in the analysis of DNA sequences that have been copied several times to a detectable level.
Positive test for blood
Since blood analysis mainly employ comparison analysis, comparing the blood of the suspect and the victim to the blood found at the scene, blood samples from both the victim and the suspect are required for reference. A blood analysis is conducted on the victims and the suspects’ blood to identify the source of the blood in the evidence. Where the blood types of the two individuals are similar, then a further comparison is made between the genetic markers found in the suspects’ blood and that of the victim. The genetic markers are then compared to the blood in the evidence to identify its source. A positive test will identify a similarity between the blood type or the genetic markers in the suspects DNA with the blood type or the genetic markers found in the DNA of the blood collected as evidence.
How to test semen evidence
Semen evidence is essential in cases involving male suspects, and especially cases dealing with sexual assault. Semen consists of components such as seminal fluid and spermatozoa. Semen evidence is crucial in these cases...