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: ccale@dnamavens.com 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 off this supersized two-parter topic with a Regional Quirkisms game of Canadian-isms. Then they move past the Great White North and talk about ASB Standards and Best Practice Recommendations. Specifically, they cover ASB Standard 015 "Standard for Examining Friction Ridge Impressions" (2024) and in Part 1, cover ASB Best Practice Recommendation 165 "Best Practice Recommendation for Analysis 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 165, First Edition 2024 https://www.aafs.org/sites/default/files/media/documents/165_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

In this episode, the guys start off with some Michigan Regional Quirkisms. They then review a 2024 paper titled "The effects of cognitive bias, examiner expertise, and stimulus material on forensic evidence analysis" by Michelle Pena, Stephanie Stoiloff, Maria Sparacino, and Nadja Schreiber Compo, from the Journal of Forensic Sciences (2024; 69:1740-1757). The research paper provided lay participants (students) and fingerprint expert participants with images of ground truth, matching and non-matching fingerprint pairs. The researchers controlled the exposure of the participant to contextual case information. Lay participants made a number of errors and seemed to be more impacted by case information compared to experts in these trials. Glenn and Eric discuss why that might be and discuss and compare other studies that might be relevant on this topic. Article: Pena MM, Stoiloff S, Sparacino M, Schreiber Compo N. The effects of cognitive bias, examiner expertise, and stimulus material on forensic evidence analysis. J Forensic Sci. 2024 Sep;69(5):1740-1757. doi: 10.1111/1556-4029.15565. Other Articles Discussed: Tangen, J. M., Thompson, M. B., & McCarthy, D. J. (2011). Identifying fingerprint expertise. Psychological Science, 22(8), 995–997. https://doi.org/10.1177/0956797611414729 Langenburg, G., Bochet, F., & Ford, S. (2014). A Report of Statistics from Latent Print Casework. Forensic Science Policy & Management: An International Journal, 5(1–2), 15–37. https://doi.org/10.1080/19409044.2014.929759

Glenn Langenburg and Eric Ray interview Angela Tonietto about her recent article on the frequency of patterns in palm prints. ("Patterning in the Distal Portions of the Palms as a Key to Palm Print Identification". 2025, 75-3, p.274.) The research analyzes the frequency of loops and deltas in the interdigital area and compares the results to past research. (Link mentioned in episode: https://demo.hugin.com/example/FingerprintEvidence)

Happy New Year 2026! The boys are back in town, with a new game: Regional Quirkisms. After discussing Minnesota quirkisms, the guys answer a listener question from Ireland: "What's the most number of corresponding minutiae that you have seen from two impressions from different sources?". This leads to a deep dive on close non-matches. The guys share their tips, tricks, and red flag warnings for dealing with close non-matches. They discuss a few examples and talk about the relevant research on this topic.

Eric Ray and Glenn Langenburg talk about their week in Orlando at the 2025 IAI Educational Conference. Hear about Quality Metrics, limited examinations, and linking cases together, and hear from some of the conference attendees.

In this episode Eric poses to Glenn a Mandela effect question concerning household cleaning products. After that, the guys celebrate the 4th of July holiday by welcoming their guests from Ireland. Four fingerprint examiners from Forensic Science Ireland (FSI), the national forensic lab in Ireland, join the podcast. The guests are Dr. Aoife Power, Dr. Craig Mullen, Mr. Columb Doherty, and Dr. Kim Connick. Glenn and the guests talk about their time at the recent European Academy of Forensic Science (EAFS) conference in Dublin in May 2025. The examiners from FSI discuss their research, posters, and presentations from EAFS. Eric is also curious about their new AFIS system and has lots of questions about their processes. The guests discuss forensic fingerprint practices in Ireland and especially working in their new national laboratory. Forensic Science Ireland: https://forensicscience.ie/ Dr. Kim Connick: kconnick@fsi.gov.ie

In this episode, the guys start with a product-based Mandela effect question. Then they welcome back long-time friend of the show and webmaster, Michael Whyte from the New South Wales police force in Australia. Michael has a question for Glenn and Eric, regarding latent-to-latent comparisons, using latent prints as 'proxy exemplars' when the exemplars are worse than the latent prints or incomplete, and various off-shoots of these questions. The guys discuss the theoretical basis and some of the legal issues that arise in both the U.S. and Australia.

In this episode, Eric stumps Glenn with a geography based Mandela Effect question. Then the guys welcome their guest commentator, Brendan Max, Public Defender and Chief of the Forensic Science Division in Chicago, Illinois. Eric, Glenn, and Brendan take a second look at the 2025 FBI/Noblis follow-up black box study for latent fingerprints. The guys had previously done a cursory review of the paper in Episode 282, and now wanted to dig in a bit into the appendices and take another look at some trends. Brendan offers his insights and shows that he’s pretty proficient with a spreadsheet too! The guys go back and forth discussing the strengths and limitations of the study and where the methodology and practice has likely improved since the original Black Box study (conducted in 2009). Article is available for free at: doi.org/10.1016/j.forsciint.2025.112457

Glenn Langenburg and Eric Ray review two articles from Cell that focus on the genetic basis for ridge development and pattern formation. 'The developmental basis of fingerprint pattern formation and variation' by Glover, et al., and 'Limb development genes underlie variation in human fingerprint patterns' by Li, et al. Our understanding of these complex processes continues to grow, and these papers further support our field and our conclusions.

In this episode, Glenn and Eric start with a quick game of “A Truth, A Lie, and a Mandella Effect”. Then they pose a question from a listener regarding interest in a forum where listeners can go and discuss the episodes of the show, ask questions, and chat “amongst themselves”. Finally they get to the long awaited Noblis/FBI study “Black Box 2” latent fingerprint error rate study. This is a re-do of the 2011 black box study for latent fingerprint performance. This study “Accuracy and reproducibility of latent print decisions on comparisons from searches of an automated fingerprint identification system” by Hicklin, Richetelli, Taylor and Buscaglia (For Sci Intl, 370 (2025), 112457), reported the performance of 156 U.S. latent print examiner participants each reviewing about 100 latent prints/comparisons resulting in over 14,000 trials. The study reports numerous statistics of performance such as sensitivity (63%), specificity (70%), false positive error rate (0.2%), and false negative error rate (4.2%). The guys also discuss some important study design differences, plus there are a lot of data in the appendices. Finally they talk about the number of false positives made in the study (n=23) and the fact that 13 of those 23 were made by one participant and how that impacted the results. Article is available for free at: https://doi.org/10.1016/j.forsciint.2025.112457

Eric Ray and Glenn Langenburg pay tribute to our colleague and friend. Kasey Wertheim passed away on March 7, 2025 and will be greatly missed. Please join us as we remember his legacy and contributions to the field of fingerprints and tell a few personal stories.

Eric Ray and Glenn Langenburg pay tribute to our mentor and friend. Pat Wertheim recently passed and will be greatly missed. Please join us as we remember his legacy and tell a few stories.

In this episode Glenn and Eric catch up after some hectic travel from recent weather issues. They do some news updates and also Eric had advice for new Patreon subscribers. Then they play an Oscar-themed round of “A Truth, a Lie, and a Mandela Effect” because it is the weekend of the 2025 Oscars. Then the guys tackle a topic which has come up many times in the past, but they’ve never actually dived into before: Simultaneous Impressions. They talk about different scenarios that can occur such as: some impressions stand alone, none stand alone, aggregation of features, and physical gaps or voids in an impression. They review the famous Mass v. Patterson case from 2005 that started the initial controversy in the field. They also have a chance to discuss John Black’s JFI research article from 2006 and other source material on the subject. Reference: Black, J.P. Pilot Study: The Application of ACE-V to Simultaneous (Cluster) Impressions. Journal of Forensic Identification, 56(6) Dated: November/December 2006 Pages: 933-971.

In this first recorded episode of 2025, Eric and Glenn start with Eric being pedantic in his “A Truth, A Lie, and a Mandela Effect”. The guys catch up on New Year stuff and then launch into a review of a research paper from New South Wales, Australia, titled “How often do fingerprint examiners disagree in routine casework?” by O’Connor and Chapman (2024) from Forensic Science International. Eric first discusses some of the important differences in casework workflow and conclusions between Aussie examiners and U.S. examiners. Then they discuss the results of the paper and the significance of the findings. At the end, they discuss solutions and ideas for resolving conflict and ultimately find that conflicting results and examiner disagreements are a normal, expected, natural part of the examination process. Find the paper at: https://doi.org/10.1016/j.forsciint.2024.112139

Glenn and Eric interview Sarah Chu, director of policy and reform with the Perlmutter Center for Legal Justice's (PCLJ) forensic science policy initiatives. Sarah breaks down her doctoral thesis on quality management and oversight in forensic science laboratories.

In this episode the guys discuss historical figures in the field of fingerprints. At the top of the episode Eric gives Glenn an Australian themed “A Truth, a Lie, and a Mandela Effect”. Glenn tells a couple of stories from his trip to London, which also inspired the topic for the episode. Because of Glenn’s time in Switzerland this fall reading old texts, he learned a lot about the early days of fingerprints. The guys discuss contributions, stories and cases from Juan Vucetich, Sir Francis Galton, Sir Henry Faulds, Sir Edward Henry, Alphonse Bertillon, Dr. Edmond Locard, and more!