Headshot of Colby Duncan, a forensic scientist at the DNA unit of a crime lab.
Colby Duncan is a forensic scientist who works in the DNA unit of a crime lab to aid law enforcement in processing evidence.
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Colby Duncan, a forensic scientist at a crime lab in Southern California, aspired to be a lawyer growing up due to her interest in criminal justice. However, when she watched The New Detectives, it sparked a profound calling to use biology to unravel criminal mysteries. With a bachelor’s degree in forensic science with a concentration in biology and a master’s degree in criminalistics, she now has her dream job. She seamlessly blends her dual passions to help bring justice to victims and their families.  

What background do you need as a forensic scientist?

There’s a misconception that you can enter this field with a criminal justice degree. While it depends on the lab, they largely look for people who have a science degree. Many of my colleagues have science backgrounds. The training is rigorous though. I am undergoing an intense 18-month training program performing mock cases, moot courts, and competency tests before I am allowed to handle official casework.

How is the collected evidence processed in the laboratory?

We process thousands of cases annually that range from homicide to sexual assault to property crimes. Our initial serology testing involves presumptive tests to identify body fluids. Positive stains undergo DNA analysis, and we check for DNA profile matches with a national database. Then we present our work with clear information about the statistics in court. 

What challenges do you face when handling evidence, and how do you overcome them?

Sample quantity used to be a huge limitation. We needed a dime- or quarter-sized amount of blood. Today, by using enhanced-sensitivity DNA analysis tools, we can process an almost-invisible speck of blood. New amplification kits offer a range of sensitivity or specificity by incorporating more dyes and primers. These kits enable multiplex detection and improve intracolor signal balance, aiding in differentiating between DNA profiles to include or exclude in the investigation. The downside of high sensitivity assays is the detection of junk DNA, but additional purification helps in those cases.

This interview has been edited for length and clarity. It expresses Colby Duncan’s personal opinions.