Double Loop Podcast

Recently, a YouTube science channel discussed five different forensic disciplines and explored potential issues with each. Eric Ray and Glenn Langenburg react to the video and share their perspectives as forensic scientists from valid criticisms to misunderstandings. Have we really been "Using The Wrong Science In Court For 50 years"? Watch the full original video here: https://www.youtube.com/watch?v=mvcesPWvUIc

In this episode, the guys start off with Regional Quirkisms from the Land Down Undah.  They then interview Cindy Cale, DNA expert from DNA Mavens, a consulting and training company in Houston, TX.  Cindy will discuss 3 topics, all related to testimony of the activity level, with respect to DNA, as well as discuss validation issues in DNA. They first discuss a recent DNA testimony case report titled "DNA analyst's refusal to answer an activity level question did not violate the defendant's right to confrontation" from the Journal of Forensic Sciences (2026; 71:1063-1069) by Ted Hunt.  The paper reviews a U.S. Court's reaction to a DNA Analyst who refused to offer any testimony regarding activity level and DNA.  Then they discuss a Minnesota case in which Cindy testified for the defense, where the State lab was attempting to introduce a complex 5+ person mixture of DNA from firearms [MN v. Exavier Porter; 55-CR-22-7394].  Defense was ultimately successful in excluding the evidence from trial.  Finally, they discuss a second Minnesota case, in which Cindy testified, where the State was attempting to introduce another complicated mixture from a firearm, and make inferences about activity level [MN v. Garry Bell; 62-CR-24-1146].  The evidence was suppressed in this case as well.  The guys make parallels to the fingerprint community and why it's important that fingerprint experts pay attention to these issues popping up in DNA. Episode References: DNA Mavens: https://dnamavens.com/ Cindy's email: [email protected] Hunt TR. DNA analyst's refusal to answer an activity level question did not violate the defendant's right to confrontation. J Forensic Sci. 2026; 71: 1063–1069. https://doi.org/10.1111/1556-4029.70266 Minnesota v. Exavier Porter; 55-CR-22-7394 order: https://forensicresources.org/resources/state-v-porter-memorandum-and-order-mn-2025/ Minnesota v. Gerry Bell; 62-CR-24-1146, Ramsey County, St. Paul, MN Minnesota v. Alexander Taylor; 69DU-CR-19-2984, St. Louis County, Duluth, MN USA (EDNY) v. Tyler Scott Johnson; 1:23-cr-00013-NRM, Brooklyn, NY. Samie, Taroni, Champod (2020) Estimating the quantity of transferred DNA in primary and secondary transfers (Sci & Just 60:128-135).  https://doi.org/10.1016/j.scijus.2019.09.008 Cale, C.M., et al. (2016) Could Secondary DNA Transfer Falsely Place Someone at the Scene of a Crime?  J For Sci 2016; 61(1): 196-203  doi: 10.1111/1556-4029.12894.

Eric and Glenn finish this two-parter episode about ASB Standards and Best Practice Recommendations. Specifically, in Part 2, they cover ASB Standard 015 "Standard for Examining Friction Ridge Impressions" (2024) and ASB Best Practice Recommendation 166 "Best Practice Recommendation for Comparison and Evaluation of Friction Ridge Impressions" (2024). The guys discuss how to use the standards, their own experiences, some of the critical requirements and recommendations, etc. ASB Standard 015, First Edition 2024 Standard for Examining Friction Ridge Impressions https://www.aafs.org/sites/default/files/media/documents/015_Std_e1.pdf ASB Best Practice Recommendation 166, First Edition 2024 Best Practice Recommendation for Comparison and Evaluation of Friction Ridge Impressions https://www.aafs.org/sites/default/files/media/documents/166_BPR_e1.pdf

Eric and Glenn start the episode with a listener email and then play a numbers themed game of Regional Quirkisms.  For the topic of this episode, the guys discuss a 2025 paper from Simon Cole and Justin Sola titled "First impressions matter: Mundane obstacles to a forensic device for probabilistic reporting in fingerprint analysis".  The article discusses practical and realistic obstacles and hurdles to developing a validated, accepted, and commercially-available statistical model for fingerprint evidence.  The article takes the novel view that most sources cite either "practitioner disinterest" (or worse: practitioner rejection) or lack of push and influence from the Courts, Daubert challenges, or Authoritative bodies.  However, once you remove those two obstacles and assume examiner 'buy-in' and Courts pushing for empirical data over subjective examiner expertise, what 'mundane' obstacles exist that most people don't realize or think about?  The article discusses a number of surprising, non-trivial obstacles that have a huge influence on the state of statistical model development in the field today. Article: Cole, S.A.; Sola, J.L.  First impressions matter: Mundane obstacles to a forensic device for probabilistic reporting in fingerprint analysis.  Social Studies of Science (2025), 55(5): 683-710. https://doi.org/10.1177/03063127251333074