Mythbusters! The Value of Negative Testimony in Forensics

Mythbusters! The Value of Negative Testimony in Forensics
Duration: 60 Minutes
Module 1 Module 1
Recorded on: 2023-07-11
Unit 1 Presentation Materials: Mythbusters! The Value of Negative Testimony in Forensics
Unit 2 Transcript: Mythbusters! The Value of Negative Testimony in Forensics
Unit 3 Workbook: Mythbusters! The Value of Negative Testimony in Forensics
Unit 4 Recording: Mythbusters! The Value of Negative Testimony in Forensics

The CSI effect is the phenomenon of jurors having unrealistic expectations of forensic science due to how TV and movies depict how criminal investigations are done. With this in mind, those working in the forensic sciences field must be able to articulate the realities, capabilities, and limitations of their profession and its related technology. This course is about debunking the myths brought about by the CSI effect by guiding forensic professionals on what to say, do, and emphasize when serving as expert witnesses in trials.

This session’s instructor is Andrew R. Reitnauer, a Certified Senior Crime Scene Analyst (CSCSA) through the International Association for Identification. He is also the CEO of Delta Forensics and an adjunct professor at four universities, instructing courses on Crime Scene Investigation, Fingerprint Analysis, and Criminalistics.

Specifics of the webinar include:

  • The CSI effect and how it impacts the outcome of jurors’ decisions in trials.
  • A video clip to juxtapose how TV presents forensic science processes and how it is done in reality.
  • A rundown of the expert witness’ responsibilities in terms of:
    • Laying the foundation and educating jurors on the reality of forensic science and the processes within.
    • Remaining objective and articulating the techniques used and how results are obtained.
    • Keeping up to date with the latest developments in forensic science, so that they can provide accurate and up-to-date information to the court.
  • The factors that impact the presence and recovery of fingerprints such as the type of surface and the composition of fingerprints.
  • The three types of fingerprints and the differences between these in terms of visibility, and the process involved in collecting these.
  • What an expert witness must articulate to the jury as it relates to the processing of fingerprints from the surface, the methods, and capturing for further examination.
  • Considerations when working with porous and non-porous surfaces and the factors that can affect the recovery of a latent print.
  • How latents are chance impressions that are fragile by nature which means they won’t always be present.
  • Evidence with special considerations such as blood and/or biological staining, tape, latex/nitrile gloves, and semi-porous surfaces.
  • What an expert witness is, and their difference from lay witnesses or eyewitnesses in terms of the information they can testify on.
  • The scope of the expert witness testimony
    • How it centers on educating the trier of fact, maintaining objectivity, and explaining findings.
    • Articulating sequential methods which impact the results of latent print processing and the factors that can affect the recovery of latent prints.
    • Presenting negative testimony where latent prints cannot be recovered or when comparisons do not yield positive results.

Points raised during the Q&A are about:

  • Getting jurors to understand the reality of forensic processes and overcome the CSI effect.
  • Extracting DNA from a fingerprint and whether reagents can impact this.
  • Whether toe prints can be recovered like fingerprints and matching it through the AFIS.
  • Conflicting conclusions between the prosecutor’s and the defense’s expert witnesses.


Other Webinars with this Presenter


Click here to view and register for other upcoming Law Enforcement webinars and recordings on the JCH Platform.


Resources and Handouts
  • Handout:  Journal of Cold Case Review (July 2015) – PDF  Link on ResearchGate
  • Handout: Factors Affecting the Recovery of Latent Prints on Firearms – PDF  DOJ Link


Audience Comments

  • “Andrew’s presentation was EXCELLENT. A must for New Police Officers.” — Robert
  • “Good advice for expert witnesses, especially for helping to teach the jury what we do in real life as opposed to what they have seen in media. Good advice when talking about the absence of findings or inconclusive results and explaining why. I was thinking that this webinar was going to be more general and less discipline-specific for fingerprints, but there was still useful information.” — Shannon
  • “The tips he provided for courtroom testimony were phenomenal. Explaining surfaces, and reasons why certain processing was completed allowing the jurors to better understand was key. I’d love to have the transcript or recording of this webinar to take additional notes.” — Pam-Alysia
  • “Learned different ways to explain results to a layperson. It was very interesting and well-presented.” — Nancy
  • “Outstanding presenter and extremely knowledgeable!” — Mark
  • “He went at a slow pace and explained what he was saying.” — John
  • “Very informative and useful to law enforcement. Bravo.” — William




This webinar is part of the JCH Summer School Program. From June 1-August 31, 2023, attendees will receive a certificate of attendance via email about one hour after the conclusion of a webinar.

Want to join us for other Summer School webinars? Check out our Summer School Calendar and register today!



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