Forensic science uses a variety of techniques to analyze evidence samples taken from crime scenes. A forensic lab typically has a team of scientists with specialist skills who piece together the significance of evidence samples including fingerprints, bullet cartridges, bloodstains and hair samples. A forensics lab has high-spec scientific equipment that can analyze and categorize the minutest samples. Forensic laboratory staff members work closely with police and other law enforcement agencies.
Rules and Regulations
A forensics lab must adhere to industry guidelines for the storage and handling of sensitive tissue samples. They must not contaminate any evidence sample taken from a crime scene through human contact or by other lab samples. When a piece of evidence first arrives, a forensics scientist will conduct tests to identify what it is; i.e. fabric, glass, metal or a particular body fluid. The sample will then pass to different departments for more complex analysis. Forensic lab scientists must keep detailed reports on the handling and processing of each evidence sample to ensure strict adherence to lab guidelines. Ensuring forensic tests are authentic is essential not only in gathering evidence to solve individual crimes. As stated on the Forensic Science website, labs can add test results to international databases to match evidence of further crimes a criminal may have committed.
Trace Evidence and Serology
Nearly all forensic laboratories have a "trace evidence" unit. Trace evidence is minute tissue samples gathered from crimes scenes such as dust fragments, hair strands or fiber elements. Forensic laboratory scientists test these tiny samples for clues as to where and how a crime happened, and who the criminal was, according to the Bureau of Labor Statistics website. Trace evidence scientists also work with skeletal remains to identify signs of injury to bones and teeth.
Serology specialists analyze bloodstains and residual samples of semen or saliva taken from crime scenes. Serology scientists also conduct DNA sequencing to match tissue samples to possible perpetrators.
Chemistry and Firearms
The forensics chemistry department analyzes blood and urine samples to detect and measure levels of alcohol, drugs or poisons present in a victim's body. They use the same procedures on synthetic materials to detect the presence of blood or other bodily fluids. Forensic chemists in this role use a range of sensitive scientific equipment including mass spectrometers and microscopes.
Firearms departments conduct testing to identify the weapon used in a violent crime. Typical duties of a firearms specialist include assessing used bullet cartridges for trace evidence and judging impact and firing distances.
Larger forensic laboratories have scientists who specialize in computer software, video and audio recordings and photographic analysis. Some have experts in arson crimes, who analyze the remains of humans and materials to determine how and when a fire started. The level of specialist expertise available will depend on the financial constraints of a particular laboratory. Some forensic labs have affiliations with universities and colleges, and larger state police departments often have a forensic laboratory on-site.