Dissertations, Theses, and Capstone Projects

Date of Degree

2-2022

Document Type

Dissertation

Degree Name

Ph.D.

Program

Criminal Justice

Advisor

Mechthild Prinz

Committee Members

Richard Li

Nicholas D.K. Petraco

Andrew Schweighardt

Subject Categories

Forensic Science and Technology | Laboratory and Basic Science Research | Molecular Biology

Keywords

Paper Evidence, Touch DNA, Workflow

Abstract

Touch paper evidence could be the source of probative human DNA but recovery is challenging and forensic laboratories instead prioritize processing by the Latent Print and Questioned Document disciplines. Recent advances in DNA collection methods and the increased sensitivity of STR typing kits have improved success rates for DNA testing of paper evidence; but prior to implementing DNA collection, laboratories have to decide in which order to examine paper for the different types of forensic evidence. This thesis developed and tested a multi-discipline workflow for processing paper evidence by DNA, Latent Prints and Questioned Documents experts. Preliminary sampling studies indicated swabbing twice with a dry swab and vacuuming the surface were comparable in DNA recovery and did not impact the subsequent paper evidence results for Latent Prints or Questioned Documents. Improved quality of detected prints was observed with 1,2- indanedione zinc chloride treatment. DNA swabbing of the paper and/or EDD film during Questioned Document processing did not improve DNA yields. The proposed paper evidence workflow of DNA processing followed by Questioned Document processing, and Latent Print processing was tested on handwritten notes from a variety of donors and on different types of paper. Large sheets of paper, like copy and notepad paper, yielded between 67% and 92% interpretable DNA profiles. Controlled indented impressions and latent prints of value were detected as expected following DNA processing, validating the workflow. The project also evaluated the stability of DNA deposited on paper by touching and showed that DNA remained stable over a twelve-month span.

Download

Share

COinS