Optical profilometry for forensic bloodstain imaging
Brayden Valea, Amanda Orrb, Colin Elliottc, Theresa Stotesburyd*
*Corresponding author:theresa.stotesbury@ontariotechu.ca
a Forensic Science Undergraduate Program, Ontario Tech University, 2000 Simcoe St N, Oshawa, ON, Canada, L1G 0C5
b Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON, Canada, K9J 0G2
c Applied Bioscience Graduate Program, Faculty of Science, Ontario Tech University, 2000 Simcoe St N, Oshawa, ON, Canada, L1G 0C5
d Faculty of Science, Forensic Science, Ontario Tech University, 2000 Simcoe St N, Oshawa, ON, Canada, L1G 0C5
ORCID: AO (0000-0002-2245-8448); CE (0000-0001-5883-0291); TE (0000-0001-6452-4389)
Data Availability Statement: Scans are available by request and data is available through https://gitlab.com/f4301/bloodstain-profilometry.
Funding Statement: We are thankful for the funding support to conduct this research. This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery and Discovery Accelerator Supplement Grants (RGPIN-2020-05816) awarded to TS. Authors CE and AO are supported through the NSERC Canada Graduate CGS-M (MSc) and CGS-D (PhD) Scholarship programs respectively.
Conflict of Interest Disclosure: The authors have no conflicts of interests to declare.
Acknowledgements:The authors would like to formally acknowledge Mitchell Tiessen, Kgalalelo Rampete, Julia Harvey, Dhrumik Patel, and Laurianne Lagace, who assisted BV with fluid property measurements throughout his undergraduate thesis. A most special thank-you goes to Dr. Iraklii Ebralidze, of the Ontario Tech University Materials Characterization Facility for training BV on the optical profilometer.
Abstract:
Understanding the physical, chemical and biological changes that occur during the drying of a bloodstain is important in many aspects of forensic science including bloodstain pattern analysis and time since deposition estimation. This research assesses the use of optical profilometry to analyze changes in the surface morphology of degrading bloodstains created using three different volumes (4, 11, and 20 µL) up to four weeks after deposition. We analyzed six surface characteristics, including surface average roughness, kurtosis, skewness, maximum height, number of cracks and pits, and height distributions from the topographical scans obtained from bloodstains. Full and partial optical profiles were obtained to examine long-term (minimum of 1.5 hour intervals) and short-term (5 minute intervals) changes. The majority of the changes in surface characteristics occurred within the first 35 minutes after bloodstain deposition, in agreement with current research in bloodstain drying. Optical profilometry is a non-destructive and efficient method to obtain surface profiles of bloodstains, and can be integrated easily into additional research workflows including but not limited to time since deposition estimation.