Drip stains formed on ice and snow: an observational study

When a crime is committed in colder climates, there is potential for bloodshed to occur in areas covered in ice and/or snow. In this work, we investigate drip stain formation on ice and snow surfaces. We examine the effects of dripping height and surface type on bloodstain size, shape and distribution. Seventy-five drip stains were created from droplets generated perpendicular to the surface across five different dripping heights and three surface types (new snow, powder snow and crust). Digital images of each bloodstain were collected and were analyzed using FIJI. Additionally, high-speed videos were taken of drip stains forming on three types of natural snow surfaces. The bloodstains observed in this study exhibited irregular characteristics compared to those seen in bloodstains on hard, non-porous and non-absorbent surfaces created in ambient laboratory conditions. The type of surface was observed to affect the diameter, circularity and distribution of satellite stains; however, dripping height did not affect these characteristics. While the estimated roughness of the snow surfaces may have influenced the formation of the bloodstains, we suggest that it is not the only surface property involved in bloodstain appearance. Our findings, while preliminary, support future investigation of bloodstain formation on cold complex surfaces.