DeKALB – In August of 2016, Sycamore residents Patricia and Robert Wilson were found murdered in their home. Trial of suspect Jonathan Hurst continued Wednesday at the DeKalb County Courthouse as DNA evidence was presented to the jury.
Wednesday morning the trial began with testimony from expert witness Laurie Lee, who has worked for the Illinois State Police Division of Forensic Science since 1990.
Lee attested to her extensive experience, as well as the efficacy of the Rockford Forensic Science Lab. During her initial testimony, Lee, who specializes in DNA analysis, explained the standard procedure she followed in testing evidence during the course of the investigation.
In the Hurst case, polymerase chain reaction (PCR) and short tandem repeat (STR) analysis was used for DNA testing.
PCR, a test used to detect genetic sequences, was used by the Rockford Forensic Science Lab to create comparable copies of DNA samples that were extracted from chosen evidence. According to the National Human Genome Research Institute, polymerase chain reaction is “a laboratory technique for rapidly producing (amplifying) millions to billions of copies of a specific segment of DNA, which can then be studied in greater detail.”
STR, which is used to find repeating DNA sequences for individual identification, was used to identify specific areas of interest in a DNA sequence and calculate the statistical frequency of potential comparisons.
Lee was responsible for handling a majority of tested evidence given to the lab regarding the Wilson case. During this specific phase of investigation, Lee’s 2017 report only provided comparisons of the DNA found in evidence to that of the Wilsons and Hurst.
In DNA samples taken from a pillow collected from the Wilson household, Hurst was identified as the “major male” DNA profile. As explained in testimony, this means there was a significant comparison drawn between the DNA Hurst provided and that on the pillow. Lee testified the statistical frequency of this comparison is “1 in 4.4 octillion” for unrelated people, which the expert witness reminded the court was “27 zeros.”
This statistical frequency reflects the probability that an individual picked at random would match the profile.
Hurst matched this profile better than others, serving as the rationale to identify him as the potential “major male” DNA profile.
Two knife handles collected from the Wilson residence were also tested, both presenting a mix of DNA. For both of these samples, Hurst was identified as the potential contributor to the major male profile when compared with his standard sample.
The probability that an individual picked at random would match the profile of the first knife handle is “1 in 6.9 septillion”. For further perspective, Earth has a population of 8 billion people –- 1 in 6.9 septillion is like picking a singular individual from a number equal to 860 trillion times the earth’s population.
The probability that an individual picked at random would match the profile of the second knife handle is “1 in 24 sextillion.”
During Defense Attorney Charles Criswell’s cross examination of Lee, the defense raised concerns over the accuracy of the statistical likelihoods due to “potential cross-contamination” because both knives were stored in the same evidence container.
Lee said regardless of the storage of the items, the comparative major male profile would remain the same.
During Lee’s testimony, lead Prosecutor Scott Shwertley asked “From your expertise, would it be fair to say as we’ve talked about your testimony, that these were significant items for your testing?”
Lee responded affirmatively.
Later Wednesday, the state called expert witness Illinois State Police forensic scientist Christopher Webb to the stand.
Webb’s testimony further explained the statistical significance of found DNA data and introduced the concept of Y-STR, which are male specific and repeating DNA patterns. This analysis used to create profiles to match DNA in evidence to standard suspect profiles. In testimony, Webb discussed how the presence of Y-STR was used to draw DNA comparisons of Hurst’s standard samples provided by the case’s investigative team to DNA patterns found on tested evidence.
During Webbs testimony, Shwertley asked “Are all methods by the Illinois State Police generally accepted in the scientific community?”
Webb responded “Yes.”
At this point in the trial, Hurst is not known to have any personal connection to victims Robert and Patricia Wilson and maintains his innocence.
Trial is set to resume at 9 a.m. Thursday at the DeKalb County Courthouse.
