Systems Thinking and DNA Mixtures: Dynamic Models, Optimization, Validation and Inference

Monday September 24th, 2018 // 8:30 am - 5:00 pm // 106

Early Registration, before August 1st$225.00
Standard Registration, after August 1st$250.00
Student Registration$200.00

This workshop introduces systems thinking with demonstrations on applying a systems approach to forensic DNA mixture interpretation, optimization and validation. Topics to be covered include validation of the DNA interpretation pipeline containing probabilistic genotyping software, focusing on current and forthcoming OSAC/ASB and SWGDAM mixture interpretation validation and verification standards and guidelines. Also included will be a review of published literature with discussions on the foundational validity of mixture interpretation and the impact of laboratory accreditation. Future directions for improving front end processing steps will also be discussed.


Learning Outcomes:

By the end of the workshop attendees will:

  1. Be cognizant of why a systems thinking approach to validation will positively impact mixture interpretation results and probabilistic genotyping outcomes
  2. Have explored the entire post-extraction laboratory system (quantification to LR computation) using a dynamic model parameterized by experimental data. We shall demonstrate that the entire process can be evaluated in a cost- and time-efficient manner by surveying common laboratory parameters such as cycle number, injection time, and analytical thresholds
  3. Have explored methods to quantify the impact of their processing decisions on the likelihood ratio and its distribution
  4. Understand the differences and relationships between sensitivity, resolution, analytical thresholds, and other relevant analytical figures
  5. Recognize the differences and relationships between accreditation, validation, optimization and verification within the laboratory’s DNA testing and interpretation processes
  6. Be exposed to a comprehensive review of mixture interpretation publications and findings from the NIST DNA Mixture Review that should be published in July 2018
  7. Be better informed on the standards for mixture interpretation, protocol development, and probabilistic genotyping validation and recognize the limits of data and mixture interpretation


Intended Audience:

DNA Technical Leaders, Laboratory Directors, DNA analysts, QA/QC managers, attorneys, academicians, consultants and aspiring DNA analysts.
Pre-requisites include: Experience with forensic DNA profiling techniques and STR data interpretation. Minimal working knowledge or experience with genotyping software would be helpful but is not required.



8:30 – 9:30amWelcome, Introductions & ObjectivesCatherine Grgicak
9:30 – 10:30amLiterature review and foundational validity of DNA mixture interpretationJohn Butler
10:30 – 10:45amBREAK
10:45 – 11:30amValidation and VerificationCharlotte Word
11:30 – 12:00pmLaboratory Accreditation and Its RoleRobin Cotton
12:00 – 1:00pmLUNCH
1:00 – 2:30pmLaboratory Optimization for Improved ConsistencyCatherine Grgicak
2:30 – 2:45pmBREAK
2:45 – 3:45pmThe Forensic Laboratory Pipeline Described as a Dynamic SystemCatherine Grgicak
3:45 – 4:30pmOptimizing the Front End of the Forensic PipelineRobin Cotton
4:30 – 4:45pmSummaryJohn Butler
4:45 – 5:00pmConcluding RemarksCatherine Grgicak


Private: Catherine GrgicakChair

Associate Professor, Rutgers University

Catherine Grgicak is an Associate Professor and Henry Rutgers Chair in the Department of Chemistry at Rutgers University in Camden NJ. Her Laboratory for Forensic Technology and Integration is a research laboratory focused on the development of systems and procedures to improve forensically relevant bio-analytical processes.

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Private: John Butler

NIST Fellow & Special Assistant to the Director at the National Institute of Standards and Technology

John M. Butler holds a Ph.D. in analytical chemistry from the University of Virginia. He has written five textbooks on Forensic DNA Typing (2001, 2005, 2010, 2012, and 2015) and given hundreds of invited talks to scientists, lawyers, and members of the general public throughout the United States and in 26 other countries so far. Dr. Butler is a NIST Fellow (highest scientific rank at NIST) and Special Assistant to the Director for Forensic Science in the Special Programs Office at the National Institute of Standards and Technology.

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Private: Robin Cotton

Associate Professor and Director of the Biomedical Forensic Sciences Program, Boston University

In the past 20 years Dr. Cotton has testified as an expert in DNA analysis in over 250 criminal cases (admissibility hearing and trials) in 35 states.  She serves on the Editorial Board of the Journal of Forensic Sciences and served two terms as an elected member of the Board of Directors of the American Society of Crime Laboratory Directors/Laboratory Accreditation Board.

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Private: Charlotte Word


Charlotte Word is currently a consultant in Human DNA Identification testing. She has performed technical reviews on many 1000’s of cases from several public and private DNA testing laboratories and has participated in the validation of various DNA test systems.  Charlotte has testified as an expert witness in over 300 trials and admissibility hearings around the country since 1990. 

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