An inside look at the Phoenix police crime lab: how detectives use DNA to solve crimes

Investigators take samples to the lab, where analysts can extract DNA and create a profile. Colton Shone breaks down how it works.
Published: Jan. 5, 2023 at 8:18 AM MST
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PHOENIX (3TV/CBS 5) -- We’re finding out more information about what exactly led police to the suspected arrested in the murder of four Idaho college students, including one with ties to the Valley.

Bryan Kohberger is the 28-year-old man arrested in the murders of the University of Idaho students in November. He was extradited to Idaho after being found and arrested in Pennsylvania. Police used genealogical DNA testing to link Kohberger to the murder. It’s the first-ever use of the technology in an ongoing investigation.

Now, we’re learning more about how the Phoenix Police Department processes its DNA evidence, taking you inside the Phoenix Police Crime Lab, where DNA samples are conducted daily.

Investigators take samples to the lab, where analysts can extract DNA and create a profile. That profile could then be added to a national DNA database called CODIS, the Combined DNA Index System, and then be used to potentially solve crimes.

Brianne Gobeski is a forensic scientist at the crime lab. She extracts samples and inputs DNA profiles into the CODIS database.

“DNA stands for deoxyribonucleic acid. It is the genetic blueprint of life. It governs our chemical and physical properties. And it is also considered the unit of heredity, which means that we get half of our DNA from our parents, from our mothers, and a half from our fathers. It actually makes us unique, and can be used for investigation purposes,”' Gobeski said.

She showed Arizona’s Family what the extraction process looks like.

“Extracting DNA isn’t too difficult, but it does take a lot of training, a lot of different chemicals and instrumentation, and some of our robotics to be able to extract DNA at this point. I’m actually setting up what’s called a plate to be able to run in some of our instruments to obtain a DNA profile,” she said.

Gobeski said creating a DNA profile can take a few days. Then, a qualifying profile can be added to the national CODIS database, which has been around since the early 2000s. She went on to say that several cold cases from decades ago were either solved or provided new leads because of advances in DNA technology.

“What will happen is that those profiles will then be searched against profiles submitted from labs across the nation. And it can be searched against crime scene samples, along with profiles from known offenders or arrestees as well,” she said.

Gobeski said there’s a considerable increase in interest in forensics in the last few years because of high-profile cases and the increasing popularity of true-crime shows.