How a Hennepin County lab builds DNA profiles to help investigators solve crimes
The Hennepin County Forensics Science Lab is crucial in helping investigators solve crimes.
"We do prioritize violent crimes first," said Hanna Sczepanski, a DNA Analyst.
When evidence is collected at a Hennepin County crime scene, it ends up in a laboratory in downtown Minneapolis, where in just a few minutes, analysts can identify blood on a T-shirt.
"I'll give it a swab and I will put it onto here," said Sczepanski. "And if it's it, it will turn green."
It's a type of science called serology. And with homicide and sexual assault investigations ongoing, there's always a backlog. But DNA analysts work quickly, protecting evidence by wearing masks, gloves and lab coats.
"A blacklight has one wavelength and we have multiple wavelengths we can look at," said Shelly Thomack, a DNA analyst.
Thomack uses an alternative light source to illuminate a t-shirt as she tries to find stains.
"You can see some things are going to fluoresce more than others," said Thomack, while examining the shirt under the light.
When she sees something, she marks it, swabs it, puts it in a tube and then conducts what's called a BCIP test to see what type of stain it is.
"This test specifically is looking for any semen," said Thomack. "You can tell this is bluer, meaning there is more semen here."
That will lead to another test, and another important step in building a DNA profile, which can be put in a database and help investigators solve their crime.
Technology in this lab is always evolving. Some of the tools they're using now will stick around for the long haul while others could become obsolete.
"Some things will stay around for 20 years because it is the best and quickest way to get something done. But we are always looking for the next way we can improve and get those results out faster," said Thomack.
The lab said it will work in the order evidence is submitted to them, but they can prioritize cases in which public safety is at risk.