Morphology of drying blood pools

Abstract

Often blood pools are found on crime scenes which may provide information concerning the events that took place on the scene. However, there is a lack of knowledge concerning the drying dynamics of blood pools. This study focuses on the drying process of blood pools to determine what relevant information can be obtained for the forensic application. We recorded the drying process of blood pools with a camera while measuring the mass. We found that the drying process can be separated into five different stages: coagulation, gelation, rim desiccation, centre desiccation, and final desiccation. Moreover, by normalizing the mass and drying time we show that the mass of the blood pools diminish similarly and in a reproducible way for blood pools created under various conditions. In addition, we verify that the size of the blood pools is directly related to its volume and the wettability of the surface. Our study clearly shows that blood pools dry in a reproducible fashion. This preliminary work highlights the difficult task that represents blood pool analysis in forensic investigations, and how internal and external parameters influence its dynamics. We conclude that understanding the drying process dynamics would be advancement in time line reconstitution of events.

DNA transfer in forensic science: A review

“…Blood dries relatively quickly depending on the temperature, humidity and presence/absence of wind [79][80][81]. A study by van Oorschot et al [82] showed that blood (15 and 30 µl) on a hard non-porous substrate will dry within 30-60 min (quicker in warmer temperatures), and that the transfer rates of blood, 5 min after deposition, declines exponentially until the deposit is dry.…”

Drying colloidal systems: Laboratory models for a wide range of applications

“…As stated by Laan et al [69], it's possible to distinguish five different drying stages, each with their own characteristics. The mass of a blood pool diminishes in a very reproducible manner, first linearly in time and then approaches a constant value.…”

Authors’ Response

“…Certainly, evaporation and coagulation can significantly affect slower aspects of BPA such as the drying of pools of blood (8), the evaporation of sessile drops with microliter or larger volume, the formation of drip trails, and wicking in fabrics. These situations can exhibit time scales on the order of minutes as well as enhanced evaporation at contact line and can thus be influenced by evaporation or coagulation.…”