Mega Edition: Bryan Kohberger Looks To Exclude Testimony From Expert Rylene Nowlin (8/14/26)

Bryan Kohberger’s defense asked the court to exclude testimony from Rylene Nowlin, the laboratory manager at the Idaho State Police Forensic Services Laboratory, concerning how Kohberger’s DNA allegedly came to be on the knife sheath recovered from the King Road crime scene. The defense specifically challenged Nowlin’s proposed opinion that the DNA was more likely deposited through direct transfer rather than indirectly transferred from another person or object. Kohberger’s attorneys argued that determining precisely how or when DNA was transferred went beyond the proper expertise of a traditional DNA analyst and entered an area where the forensic community lacked sufficient scientific consensus. They relied heavily on a 2024 National Institute of Standards and Technology report addressing DNA transfer, persistence, prevalence and recovery, which cautioned against analysts offering conclusions about the activity or mechanism that caused DNA to appear on an item. The defense maintained that Nowlin’s opinion would therefore be speculative, potentially misleading to jurors and unfairly prejudicial because it could make the DNA on the sheath appear more incriminating than the underlying science justified.

Kohberger’s lawyers also sought to prevent witnesses from describing the sheath evidence using terms such as “touch DNA” or “contact DNA,” arguing that those labels could misleadingly suggest that Kohberger necessarily touched the sheath himself. They further contended that Nowlin’s proposed testimony was not legitimate rebuttal evidence because her opinion about direct DNA transfer effectively supported a central part of the prosecution’s affirmative theory of the case and should have been presented and disclosed accordingly. Judge Steven Hippler ultimately declined to exclude Nowlin’s opinions, finding that expert testimony concerning the relative likelihood of direct versus indirect DNA transfer could help jurors understand the significance of the DNA evidence. However, the judge agreed that terminology such as “touch DNA,” “contact DNA” and “trace DNA” could create confusion and directed the parties to have their witnesses avoid those labels. The ruling therefore allowed Nowlin to testify about DNA transfer while restricting some of the terminology prosecutors could use to characterize the genetic material recovered from the sheath.



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