Double Loop Podcast

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%).

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 20

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!

The guys start out with a quick explanation of why Glenn’s sound is so bad (he’s in Switzerland recording). They also start the new “season”, post-IAI with a new game: "Truth, Lie, or Mandela Effect?" Eric talks about his fall conference junket and then the guys finally catch up on the IAI. They discuss their favorite lectures, workshops, and activities at the 2024 IAI Conference in Reno, NV. They summarize some of their standout lectures that they attended. Glenn then discusses how the Double Loop Podcast vendor booth went with Rebecca Coutant running it during the conference. Rebecca also was “Our Girl Friday”, doing her impromptu interviews with conference attendees.

Eric and Glenn are back from a little summer break, prepping for the 2024 IAI Conference in Reno. They do a final “Where in the Whorld?” game. Then they jump into a recent paper on “Inconclusive” decisions (Swofford, et al. (2024) “Inconclusive Decisions and Error Rates in Forensic Science”, Forensic Science International: Synergy (vol 8; 100472)) authored by several members of NIST. The paper proposes a method for computing and communicating error rates when “inconclusive” decisions are made. The paper also focuses on making clear distinctions between “method performance” versus “method conformance”. The guys discuss their views on the method and the implications the paper may have for fingerprint examiners and their agencies. Swofford, H. , Lund, S. , Iyer, H. , Butler, J. , Soons, J. , Thompson, R. , Desiderio, V. , Jones, J. and Ramotowski, R. (2024), Inconclusive Decisions and Error Rates in Forensic Science, Forensic Science International: Synergy, [online], https://doi.org/10.1016/j.fsisyn.2024.

Glenn and Eric are joined by Angela Hilliard to discuss her experiences with a cold case from the Pacific Northwest. Genetic genealogy provided a suspect's name from a cold case double homicide, and a latent palm print was left on the victim's van. Angela walks us through her initial erroneous exclusion, the subsequent identification, court testimony, and the resulting press coverage. A must-listen episode for examiners on how to handle erroneous conclusions, even in high-profile cases. (Apologies for the audio in this episode. We did not realize until later that some of audio was poorer quality than normal.)

This super-sized episode has the guys interviewing several people from a recent Expert Working Group on Human Factors in the discipline of DNA. Glenn starts by giving Eric his “Where in the Whorld” question and they catch up on some recent travels. Glenn also explains why this episode does NOT feature a continuation of the previous episode on the Peacemaker case, but instead pivots to a different DNA topic. In May 2024, NIJ/NIST released a Human Factors and Forensic DNA Interpretation report. (The) Niki Osborne, Ph.D., the project lead and contractor for NIST (Natl Institute of Standards and Technology) describes how the project came to be and how NIST selected the Expert Working Group (EWG). Then, two members of the EWG, Jarrah Kennedy, Assistant DNA Supervisor, Kansas City Police Crime Laboratory, and Michelle Madrid, DNA Technical Leader, Los Angeles County Sheriff’s Department, discuss the various recommendations in the report. The group covers all sorts of fun topics within DNA discipline such bias

Eric and Glenn start the episode with a Where in the Whorld that leads to a little catching up. Glenn was in NYC recently (saw the Harry Potter show on Broadway, indulging his “magician” side) and Eric has been doing the conference circuit. Eric is also soliciting fingerprint experts for a research project on ‘estimating image resolution’ based on ridge density. The guys also got a listener voicemail that they discuss (and roundly disagree with). Finally they discuss the main topic for the show, a homicide case and trial that Glenn testified in: South Dakota v. Jeremiah Peacemaker. Glenn covers his involvement and the fingerprint evidence. In the second half of the show, the guys welcome Anjali Ranadive, who was the DNA expert for the defense, to discuss the DNA evidence and testimony in the case. Both Anjali and Glenn had an opportunity to witness the DNA testimony at trial and were astounded by the “scientific conclusions” drawn, and testified to, by the DNA analyst. Contact Anjali Ranadive: scilawf

Today Eric and Glenn finish Part 2 on the 2023 Report of the Texas Forensic Science Commission dealing with a latent print case. They continue to discuss the TFSC report that followed an investigation into a complaint filed against the latent print contractor(s) in the Joseph Webster case. In part 2, the guys focus on Glenn's examination which concluded that the Webster palm mark was a complex mark and that 3 critical things will shape the conclusion rendered by an examiner: 1) which images were used; 2) which features were relied upon; 3) how the examiner applied the ACE-V methodology. Finally, they discuss the over 2 dozen recommendations that the Commission made for fingerprint examiners in Texas to follow in latent print examinations. www.txcourts.gov/media/1457617/fi…-as-of-12623.pdf

Today Eric and Glenn start Part 1 of a two-parter on the 2023 Report of the Texas Forensic Science Commission dealing with a latent print case. First the guys do some catching up and play Where in the Whorld. They also discuss an email from Simon Cole and inquire on the impact of the recent AI paper on fingerprints. Then they discuss the TFSC report that followed an investigation into a complaint filed against the latent print contractor(s) in the Joseph Webster case. The webster case was a homicide cold case that eventually broke with a CODIS hit and a subsequent apparent bloody palm print at the scene of the crime. Initially the palm print was not identified to Webster, but then after the CODIS hit occurred to Webster and a second person, the latent print evidence was re-visited in 2013, and an identification was declared (pursuant to reviewing additional palm print exemplars of Webster). Testimony occurred in 2016 by a project manager, but not any of the original examiners. In 2020, a contractor for

Eric Ray and Glenn Langenburg sit down for a chat with Steve Johnson about face examiners, face comparisons, and the IAI. Steve's background includes latent prints, forensic art, face comparison, crime scene, and many positions with the IAI. He shares the future of the face discipline and how the IAI is working towards a certification process.

Eric and Glenn host another guest from Australia in today’s episode. After another round of Where in the Whorld and a few stories from Eric’s childhood, the guys welcome Chloe George from New South Wales Police Force, Australia. Glenn saw Chloe present at IAFS, where her presentation on phalange pattern classification won best Oral (Presentation). Chloe introduces a system of phalange pattern classification first described by Marie Ploetz-Radmann in 1937. She walks us through the system and the 12 general pattern types in phalanges and then also shares her personal data and testing that she performed. A copy of her IAFS presentation can be found here: https://docs.google.com/presentation/d/1yrUsOFM5alJV1rQcrTGXiQkDb-3DuWUO/edit#slide=id.p5

In this post-New Year’s Eve 2023-2024 episode, the guys start by discussing their New Year’s Eve and play another round of Where in the Whorld. They then introduce their guest from the New South Wales Police Force, Andrew Chapman. Glenn had the benefit of seeing Andy’s presentation at IAFS in Sydney. Andy presented on a fingerprint black box error rate study conducted with laypeople, trainees, and experts in New South Wales, Australia. The guys discuss various statistics in the study, especially when comparing across the participant groups. The Aussie data are very similar to U.S. examiner data and the guys draw some parallels to other research. The guys also discuss some novel aspects to the study design that make this one such a fascinating study.

Glenn and Eric start by talking about their Christmas plans, followed by a game of “Where in the Whorld”. They then welcome their guest, Dr. Bethany Growns, a lecturer and psychologist at the University of Canterbury, in New Zealand. Bethany joins the show to discuss her research on matchers, super-matchers, and research she has conducted with novices (lay people), fingerprint, firearms, and facial recognition experts. She discusses the advantages of natural ability v. trained expertise and how it impacts one’s ability to perform matching tasks in the expert’s domain v. other domains. The guys ask questions about how to utilize this research to impact training programs. Finally, they discuss more aspects of the IAFS conference where Glenn met Bethany. Growns B, Dunn JD, Mattijssen EJAT, Quigley-McBride A, Towler A. Match me if you can: Evidence for a domain-general visual comparison ability. Psychon Bull Rev. 2022 Jun;29(3):866-881. doi: 10.3758/s13423-021-02044-2. Epub 2022 Jan 7. PMID: 34997551; PMCID

Eric and Glenn respond to the recent allegations that a computer science undergraduate at Columbia University, using Artificial Intelligence, has “proven that fingerprints aren’t unique” or at least…that’s how the media is mischaracterizing a new published paper by Guo, et al. The guys dissect the actual publication (“Unveiling intra-person fingerprint similarity via deep contrastive learning” in Science Advances, 2024 by Gabe Guo, et al.). They state very clearly what the paper actually does show, which is a far cry from the headlines and even public dissemination originating from Columbia University and the author. The guys talk about some of the important limitations of the study and how limited the application is to real forensic investigations. They then explore some of the media and social media outlets that have clearly misunderstood this paper and seem to have little understanding of forensic science. Finally, Eric and Glenn look at some quotes and comments from knowledgeable sources who also hav