Marta V. (she/her)

Forget what you’ve seen on television. My job only takes place in a laboratory. Also, I don’t collect evidence from crime scenes. This is done by trained police officers. The items of interest from a crime scene are called exhibits. When I am examining exhibits, I work alone. At other times I work as part of a team. All the examinations I perform are reviewed by another trained biologist. I also consult with other more experienced forensic biologists on complex cases as needed. As I have become more experienced in my role, I now provide training and mentoring to others. I also consult with other team members on cases they are working.

The material I look for on items from crime scenes is biological in nature. This means it comes from a living person. The types of biological fluid I look for on the exhibits are blood, semen, or saliva. Other types of biological material I may encounter may not be relevant to my examination. These are things such as plant material or insects, depending on where the exhibit was collected. Examples of non-biological material I encounter include soil, glass, fibers, paint or building material. Depending on the case, I also recover the non-biological material that may be relevant to the case.

I use various tools such as alternate light sources to help look for biological fluids. For example, semen and saliva can fluoresce or glow and blood can appear black under certain lighting conditions. I have several chemical tests to determine if the body fluid I find may be blood or semen. To confirm the presence of human semen for example, I look for the sperm under a microscope at a high magnification. I also recover and examine hairs on exhibits. I then use a microscope to determine if the hair is of human or animal origin. I further examine the human hair roots to determine if they are suitable for DNA analysis. Whether DNA can be recovered from hair depends on the growth phase of the hair. It also depends on whether there is biological material attached to the hair root.

Biological fluids and the roots of suitable hairs contain nuclear DNA that is used to generate DNA profiles. The process of extracting DNA from the samples is done by the analytical section. Here, they perform DNA analysis. Once that is complete, the results from DNA analysis are examined by Biology Forensic Specialists. They determine if suitable DNA profiles were generated from the samples I took. These DNA profiles are then compared to known DNA profiles in the case and to DNA databases to look for DNA matches. This can create links or associations that will further the investigation of the alleged offence. Most of what you may have seen on television is not accurate. For example, the results from these examinations are not instantaneous. Also, not every sample can provide DNA.

Examples of exhibits that are submitted to the lab for analysis include clothing that may have been seized at the scene of a crime, or from a complainant or suspect’s body. Other examples include potential weapons such as a gun or knife. Samples may also come from airbags that have been activated. The investigator may take swabs from surfaces that may contain DNA evidence. For example, a swab of potential blood from a doorknob.

Attention to detail is very important. A single mistake can mean that important evidence might not be able to be used in court. To prevent this, we follow precise steps to prevent contamination of the samples. I follow a strict series of steps as I recover, identify, and preserve materials that might help explain the crime scene. It is very important to keep detailed notes at every stage.

As I perform my examinations, I document what I observed on the exhibits I examined. I also document the tests I perform and their results. A copy of my file is then reviewed by another forensic search biologist before the samples can be processed by the analytical section. My notes are also used by the Biology Forensic Specialists that analyze the DNA profiles. Once their analysis is complete, they send a report to the investigator of the case detailing the findings. We keep very clear records of who examined a sample, when it was examined, and the tests that were performed. All this record keeping is very important for court testimony.