DNA (Deoxyribonucleic Acid) can be obtained from biological specimens left at crime scenes such as murder, aggravated battery, sexual assault, hit and run, burglary, etc. The biological specimens most often encountered include blood evidence, seminal fluid, or saliva. In serology, these body fluids are identified and, if needed, the biological material is then further tested utilizing DNA analysis (STR or short tandem repeat analysis). In additional to blood evidence, the crime laboratory will conduct serological examinations on other body fluids. The examination most frequently requested is for the identification of semen in connection with sexual assault cases. The third body fluid that is tested for is saliva. Certain items of evidence may contain saliva (baccal cells). These exhibits may be used for DNA analysis and include such items as cigarette butts, drinking straws, soda/beer cans, masks, bottles, etc.
Determination of the type and characteristics of blood, blood testing, bloodstain examination, and preparation of testimony or presentations at trial are the main job functions of a forensic serologist, who also analyzes semen, saliva, other body fluids and may or may not be involved with DNA typing. It must be recognized, however, that in many crime labs, there may be no clear distinction between job title and job function.
There's no substitute for Forensic Serology, whether for medical or forensic purposes. Blood’s presence always links suspect and victim to one another and the scene of violence. Bloodstain patterns tell a lot about position and movement during the crime, who struck whom first, in what manner, and how many times.
The Crime Laboratory Analysts will identify biological materials and determine species of origin. The Crime Laboratory Scientists will receive, secure, handle, inventory, return and preserve physical evidence collected in criminal investigations and submitted to the crime laboratory for examination or analysis. The basic principle of Forensic Serology in the modern forensic lab is to locate, identify the body fluid stains (such as blood, semen, saliva, vaginal secretions etc.) and save for the purpose of DNA analysis. There is no crime in the world which can be committed without leaving any trace behind. On the basis of this principle, forensic serologist’s job is to find, locate and identify the body fluids and other traces. “Failure of not finding the physical evidence at the crime scene does not mean that it is not present, physical evidence is always present when humans are not. Physical evidence cannot lie and purge itself when human are. Physical evidence is factual and can never be absent from the crime scene. (Prof. Locards)” Failure of not finding the physical evidence due to the lack of training can diminish its value. That is why the state of the art training is very important and integral part of this project.