Probabilistic genotyping and the power of modern DNA technology: A case study in overturning a wrongful conviction for murder in Texas

C.E. Credits: Florida CE P.A.C.E. CE
Speaker
  • Assistant Director, Henry C. Lee Institute of Forensic Science, Associate Professor, Forensic Geneticist, Henry C. Lee College of Criminal Justice & Forensic Sciences, University of New Haven
    BIOGRAPHY

Abstract

In late 2019, nearly a decade into a life sentence, Lydell Grant was released from a Texas prison after being convicted of a murder that he did not commit. The victim, Aaron Scheerhorn, was stabbed multiple times in a parking lot outside of a bar in Houston. A DNA mixture was recovered from the victim’s fingernails but was too complex to analyze at the time of the original trial. Mr. Grant’s conviction resulted primarily based on the testimony of six eyewitnesses, all of whom identified him as the killer. During the trial and the entirety of his imprisonment, Grant vehemently denied his involvement in the crime. In 2018, forensic DNA expert Dr. Angie Ambers and a legal team from the Innocence Project of Texas requested access to evidentiary samples collected from the victim during autopsy. Mixed DNA data generated from the victim’s fingernails was sent for analysis using a “probabilistic genotyping” software program called TrueAllele®. Analysis of the raw data from this DNA mixture not only excluded Mr. Grant as the source of the foreign DNA, but resulted in a CODIS database hit that identified the actual murderer of Mr. Scheerhorn. This presentation will provide an overview of Grant’s case, as well as a discussion of subjectivity issues with previous DNA mixture interpretation approaches and the improved (more  objective) analytical capabilities provided by probabilistic genotyping software programs.

Learning Objectives:

1. Identify issues regarding DNA mixture interpretation

2. Learn about current probabilistic genotyping programs for forensic casework

3. Understand how probabilistic genotyping can assist with post-conviction DNA testing


Show Resources
You May Also Like
MAY 11, 2021 10:00 AM PDT
C.E. CREDITS
MAY 11, 2021 10:00 AM PDT
Date: May 11, 2021 Time: 10:00zm PDT Your samples are some of the most valuable assets in the laboratory. After spending countless hours on extraction and preparation, your conclusions could...
SEP 14, 2021 7:00 AM PDT
C.E. CREDITS
SEP 14, 2021 7:00 AM PDT
Date: September 14, 2021 Time: 7am PDT, 10am EDT, 4pm CEST A conventional thermal cycler has long been a commodity product in the lab and end-point PCR techniques can be completed almost wit...
OCT 20, 2021 10:00 AM PDT
C.E. CREDITS
OCT 20, 2021 10:00 AM PDT
Date: October 20, 2021 Time:10:00am (PDT), 1:00pm (EDT) As the prevalence of Diabetes continues to rise in many areas across the globe, healthcare providers continue to look for methods that...
JUN 09, 2021 7:00 AM PDT
C.E. CREDITS
JUN 09, 2021 7:00 AM PDT
Date: June 9, 2021 Time: 09 June 2021, 7am PDT, 10am EDT, 4pm CEST cells with dramatic implications on the validity of past cell culture related research. The fact that at least 509 cell lin...
OCT 12, 2021 9:00 AM PDT
C.E. CREDITS
OCT 12, 2021 9:00 AM PDT
Date: October 12, 2021 Time: 9:00am (PDT), 12:00pm (EDT) SCIEX’s next-generation Biologics Explorer software is an innovative platform for the comprehensive and deep characterization o...
SEP 17, 2021 12:00 PM CST
C.E. CREDITS
SEP 17, 2021 12:00 PM CST
Date: September 16, 2021 Time: 9:00pm (PDT), 12:00am (EDT) 3D cellular models like organoids and spheroids offer an opportunity to better understand complex biology in a physiologically rele...
Loading Comments...
Show Resources