Author ORCID Identifier

https://orcid.org/0009-0001-7765-0138

Semester

Spring

Date of Graduation

2026

Document Type

Thesis (Campus Access)

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Forensic and Investigative Science

Committee Chair

Tina Moroose

Committee Member

Kenneth J. Ryan

Committee Member

Jamie Belrose

Abstract

Sexual assault evidence has become increasingly common in forensic laboratories. During criminal investigations, clothing and bedding may also be recovered, some of which may have been laundered. Due to the nature of this evidence, routine DNA testing may not be conducted. However, scientific literature has shown that spermatozoa may persist on fabric after laundering, allowing for male DNA to be recovered.

In the present study, cotton and polyester substrates stained with 200 μL of donor semen were subjected to laundering under air-dried and machine-dried conditions. After laundering, the M-Vac® wet vacuum system was investigated as an alternative collection method for the laundered semen evidence. Unlike traditional collection methods (i.e. swabbing, cutting, or tape lifting), the M-Vac® does not require the analyst to visually identify a stain, which is especially useful for laundered semen stains that may not fluoresce under an alternate light source. The M-Vac® allowed for DNA to be recovered, with quantities ranging from 1.4x10-4 to 0.014 ng/μL. Despite the low quantities of DNA recovered after laundering, 16 samples generated ≥ 80% of a profile matching the male donor, five of which were complete profiles.

To assist with the interpretation of low-level data, probabilistic genotyping with the TrueAllele® software was utilized. TrueAllele® allowed for the interpretation of peaks appearing below internally validated thresholds. Single-contributor interpretation requests were performed, resulting in 56% of samples generating inclusionary match statistics. No statistically significant differences were noted between each sample group: cotton, air-dried; cotton, machine-dried; polyester, air-dried; and polyester, machine-dried.

This preliminary study demonstrates the need for continued research into the recovery of different biological fluids after laundering with the M-Vac®. Future directions also include investigations into the persistence of biological fluid mixtures after laundering, followed by TrueAllele® interpretation.

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