DNA ruled out suspects in Sophie Sergie murder case, until 2018
Some of the stories from the Sophie Sergie murder trial are potentially traumatizing to listeners.
Criminologists from the Alaska Scientific Crime Detection Laboratory reviewed their work to identify semen, and later DNA, on the victim.
Jurors in the Sophie Sergie murder trial heard more forensic science Thursday. Criminologists who worked for the state crime lab in 1993 testified about their search for spermatozoa and the fledgling science of DNA matching at that time.
Sophie Sergie was found shot to death in the bathroom on one of the women’s floors in the Bartlett Hall dormitory at University of Alaska Fairbanks on April 26, 1993. She was undressed and investigators found evidence of rape.
So days later, the scientists looking through microscopes at the state crime lab were trying to confirm that semen was found on the victim.
"Serology is the study to identify basic body fluids and the first tests are for looking for blood, and the last three tests, you're looking for semen, or seminal fluid."
That’s Hayne Hamilton, now retired, she was a forensic serologist at the Alaska Scientific Crime Detection Laboratory.
Over the years, Hamilton has written six reports about the samples she prepared and examined for this case.
Hamilton testified that in 1993, it required a sample of bodily fluid about the size of a quarter to develop a DNA profile. Samples of fluids taken at the crime scene and autopsy were enough to confirm presence of semen, but not enough to create a DNA profile.
The case went cold until 1999 when investigators had developed new leads and collected DNA samples from several men close to the crime.
Within those years, amplifying techniques allowed for profiles to be developed from smaller amounts.
“There were people starting to be developed that they wanted to compare these samples to,” she said.
It was easy to rule out suspects by looking at their DNA.
“Every unique marker on the DNA chain is unique to that person. If that person has even one marker that does not match in that sample, it does not match the person, they are excluded. If they don't have that type, they don't have that type, she said
Over the years, more than a dozen suspects were ruled out by their DNA not matching what was found on the victim.
“They were all excluded.”
Serologists found DNA on the victim’s right breast that has not yet been matched to anyone, even the defendant, Steven Downs.
But in 2018, the profile developed from the semen found in the victim partially matched the profile of a woman who submitted her DNA to a genealogy website. That woman was Steven Downs’ aunt. Downs was living in the same dormitory at the time of the killing, and became a prime suspect. He was arrested in 2019.
The courtroom is closed to the public to prevent COVID-19 sickness. But the court is video streaming the trial on the Alaska Court System website. Prior permission to record the proceeding for this story was granted.