5. Conclusion
Optical profilometry provided detailed topographical scans of degrading
whole bloodstains, an area not yet explored in the forensic literature.
We were able to characterize the drying of three different bloodstain
volumes through the analysis of relevant surface characteristics.
Importantly, this work investigated the timewise degradation of whole
blood, expanding on previous work that explored the drying of blood and
other biocolloidal fluids. Using this method, we observed that most of
the timewise changes to drying bloodstains occur within the first 35
minutes after deposition. Over a longer time period, the overall surface
morphology shows little variation, currently limiting the use of optical
profilometry as a standalone technique in TSD estimates. Optical
profilometry has previously been paired with SEM [24] and AFM
[25] for imaging purposes; combining these two techniques could be
useful for a more detailed analysis of crack and pit formation. In
addition, factors such as viscosity, temperature, PCV%, and blood
diseases affect the drying of bloodstains [8,9,11,26]. Further
research into these factors should be undertaken to understand their
effects on the topography of degrading bloodstains [8,9,11,26].
Additionally, the influence of topography on spectral changes for TSD
estimation should also be considered. Finally, various substrates, such
as those with rougher surfaces, may lead to interesting crack formation
and timewise trends with bloodstain degradation that could be captured
using optical profilometry.