Steven H. Downs of Auburn, Maine, who is charged with the murder and sexual assault of an Alaska woman 29 years ago, was not the man whose DNA was found on the victim’s breast, an expert testified in court Friday.

William Watson is sworn in Friday in Fairbanks Superior Court in Alaska as a forensic DNA expert in the murder and sexual assault trial of an Auburn man. Screenshot used by permission of Fairbanks Superior Court

Forensic DNA expert William Watson, who oversees the New Mexico crime lab’s DNA database testing, appeared in Fairbanks Superior Court as the final witness for the defense before it rested its case midday.

Watson said he examined data collected from a swab taken from the body of Sophie Sergie, 20, of Pitkas Point, Alaska, that was sent from the Alaska Scientific Crime Detection Laboratory to a private DNA testing firm in Utah for analysis.

That firm, Sorenson Forensics, generated a report in 2012 that showed some locations of DNA markers, but determined the results were “inconclusive” because there was insufficient information from the sample to make comparisons to known DNA profiles.

The report said there were two or more contributors to the sample from the victim and that at least one of those unknown contributors was male.

Watson said he used the data from the Sorenson report to compare to known DNA profiles of Sergie and Downs.


He said he assumed one of the contributors was Sergie. Based on that assumption, he concluded the male contributor could not have been Downs because the DNA markers found in the sample didn’t match up with those contained in Downs’ DNA profile.

“I would say, in my opinion, that Mr. Downs is excluded as a contributor to this mixture,” Watson said.

Chief Assistant Attorney General Jenna Gruenstein grilled Watson about the reliability of his comparison, pointing out that the Sorenson lab had deemed their results “inconclusive” because the data from the specimen fell below the threshold of levels required by their lab’s protocols.

Watson’s testimony suggests a man other than Downs had left his DNA on Sergie before she was found dead in the bathtub of a women’s bathroom on the second floor of Bartlett Hall at the University of Alaska at Fairbanks on the afternoon of April 26, 1993.

Gruenstein asked Watson whether a first responder or crime scene analyst might have inadvertently deposited his DNA on the victim, accounting for the unknown male DNA found on her breast.

Watson said that was possible.


Downs’ semen was found in Sergie’s vagina, linking him to her murder and sexual assault.

He told investigators in 2019 that he had never met Sergie and couldn’t explain how his DNA could have been found in her.

In 2000, a DNA profile had been built from foreign bodily fluids found inside Sergie. That profile had been loaded into the national DNA database of criminal offenders, but no matches resulted.

Police had submitted the crime scene DNA from Sergie’s killing in September 2018 for a new technique of so-called “genetic genealogy” analysis that had recently helped solve a double-murder cold case in Washington state. In December of that year, Downs’ name came back from the analysis through a random hit after his aunt had submitted her DNA to a genealogy website.

Downs, now 47, had been a first-year student at the school in the spring of 1993 and had lived one floor up from the bathroom where Sergie’s body was found.

Investigators said she had been visiting a friend who lived on the second floor and that she was last seen late on April 25, 1993, leaving that room to smoke a cigarette. Her body was discovered the next day by custodial staff.


Sergie had been fatally shot in the back of the head with a .22-caliber gun and stabbed in the cheek and eye, according to investigators. Her sweatpants and underwear had been pulled down to her knees; her bra pushed up above one breast.

Under direct examination, witnesses for the prosecution testified during the trial that there was no trace of semen found in her underwear, suggesting the semen found in her had been deposited at the time of her death.

Defense attorneys pointed to evidence that intact sperm could be found up to three days after they’ve been deposited in a body, suggesting she could have had consensual sex a day or two before she was killed.

No other physical evidence recovered from the crime scene was matched to Downs. The defense says that points to his exoneration, but prosecutors say it doesn’t point to any other suspect.

The state called two rebuttal witnesses Friday before finally resting its case against Downs.

Judge Thomas Temple told the jury it should expect to hear closing arguments by the two sides on Monday morning and also be instructed on the law before starting deliberation.


Jurors took copious notes during three weeks of testimony by dozens of witnesses, including investigators, forensic scientists, former students at the school, a gun dealer and Downs himself in recorded police interviews.

Sergie had been a student at the school the previous year, but had taken a year off to work so she could get health insurance to help pay for orthodontia.

Downs was arrested in Auburn in February 2019 and extradited to Fairbanks. His trial got underway last month, but was delayed twice by COVID-19 exposures among trial participants.

Ten women and five men comprise the jury, including three alternates who are expected to be dismissed Monday before the jury is given the case.

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