DNA Basics: Understanding DNA Evidence in Criminal Investigations and Prosecutions

DNA Basics: Understanding DNA Evidence in Criminal Investigations and Prosecutions
Duration: 60 Minutes
Module 1Resources
Recorded April 5, 2018
Unit 1Slide Deck: DNA Basics
Unit 2Recording: DNA Basics
Unit 3Webinar Notes: DNA Basics - Understanding DNA Evidence in Criminal Investigations and Prosecutions

Law enforcement encounters all types of cases, from the most no-brainer infractions and misdemeanors to complex and grave felonies. It has always been the goal to serve justice, but in certain instances, the stars aren’t aligning up as necessary to make a perpetrator accountable for the crime committed. Back in the old days, due to lack of evidence or witnesses, the culprit would’ve lived as a free man.

Fortunately, DNA testing and DNA evidence are being used in the present to make powerful and compelling evidence needed in investigations. As with any new discovery or technology, people have reservations about it. They question its usefulness and given how DNA testing and evidence is being utilized, its credibility and accuracy.

Chris Lindberg is the speaker for this webinar where he unpacks the science involved in DNA evidence. Chris will expound on the end-to-end process from sample collection, analysis, to presentation, and DNA testing’s benefits, pitfalls, and challenges. Chris is the Deputy District Attorney from the San Diego County DA’s Office and with his prolific career in prosecution has developed an expertise in DNA related cases.

Some of the points Chris raised in this session include:

  • An introduction to how DNA is used as a tool in the criminal justice system to solve crimes, convict the guilty and acquit the innocent.
  • Case studies that serve as an overview of the utility of DNA testing in solving two gruesome murder cases that were traced to a common suspect.
  • The usefulness of DNA evidence in various crimes.
  • What DNA is and its types – where coding is mainly in-charge of protein production and non-coding is the focus in DNA testing.
  • Items where DNA can be collected and collection methods.
  • How evidence examination is done and ways contamination is prevented.
  • The analytical process of DNA extraction, quantification and amplification, and all the particulars involved in these procedures.
  • How to get a reference sample to compare sample results from and factors to consider when getting reference sample.
  • How computers have improved DNA testing immensely through Probabilistic Genotyping.
  • An explanation of the Likelihood Ratio that is unit of measure of the relationship or the match of a DNA sample collected as evidence to the DNA sample of a suspect.
  • A comparison of the match results obtained from traditional DNA testing and using a software.
  • An illustration of what DNA testing results look like.
  • The technical terms, scientific notations, and units of measurements used in the results.
  • How DNA evidence and testing is important in casework and the other procedures that must be done to validate testing.
  • Defining the purpose of DNA testing and discerning if doing so can be useful or just worsen a case based on various considerations and circumstances.
  • What lawyers must look into and request when reading DNA test results.
  • The components of the Kelly-Fyre rule which is used as the threshold for admissibility of DNA evidence and results.
  • Methods to effectively present DNA evidence to court by keeping it simple, direct, results-oriented, descriptive and if applicable, using an analogy to explain complex subjects to the jury.
  • Ways that DNA evidence is being attacked by defense based on its relevance, reliability, and conclusions.
  • Publications that try to disregard the benefits of DNA testing softwares.
  • Ways that the DNA testing software providers and companies are fighting these accusations.
  • Poll questions were asked to measure the attendee’s familiarity with DNA, use of DNA in casework and Probabilistic Genotyping, as well as gauging their interest in the future of DNA analysis and the presentation.
  • Chris entertained questions from the audience regarding:
    • Using DNA testing for fired cartridge cases and shell cases
    • The variability of the degradation rate of DNA in evidence
    • The changes and improvements in DNA testing in the last decade
    • Using DNA evidence not only to convict those guilty but also absolve those who are innocent
    • The use of population frequency databases based on ethnicity in the DNA database
    • Using DNA to determine the ethnicity of an alleged subject
    • Using DNA in non-criminal cases such as identifying war dead, plane crash victims, and missing persons
    • The debate on how DNA evidence will be collected and kept in California
    • The success of using DNA testing in solving cold cases up to 40 years old
  • There were audience comments on topics that have been touched upon in the Q&A including phenotyping and two providers as Parabon Nanolabs and M-Vac
Additional Resources
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