Validation of Bloodstain Pattern Analysis: Drip Stain, Drip Pattern and Drip Trail

Bloodstain pattern analysis (BPA) is a field of forensic science that interprets bloodstains found at crime scenes and can be used to reconstruct crime scenes and corroborate witness, victim, and/or suspect statements. BPA has been used in the interpretation of evidence for many years but there are criticisms regarding the methods used for analysis due to a lack of validation studies in the field which also leads to the analysis being open to contextual bias. This study looked at features of drip stains, drip patterns and drip trails, including the bloodstain 􀄂􀆌􀄞􀄂􀀃􀄂􀅶􀄚􀀃􀀦􀄞􀆌􀄞􀆚􀍛􀆐􀀃􀄚􀅝􀄂􀅵􀄞􀆚􀄞􀆌􀍘􀀃􀁞􀄂􀆚􀄞􀅯􀅯􀅝􀆚􀄞􀀃􀆐􀆚􀄂􀅝􀅶􀀃􀄚􀅝􀆐􀆚􀆌􀅝􀄏􀆵􀆚􀅝􀅽􀅶􀀃􀄨􀅽􀆌􀀃􀄚􀆌􀅝􀆉􀀃􀆉􀄂􀆚􀆚􀄞􀆌􀅶􀆐􀀃􀄂􀅶􀄚􀀃 distance between each bloodstain for drip trails was also determined. The drip stain and drip patterns were made on two substrates, tile and wood, from three heights: 50 cm, 100 cm and 150 cm. The drip trails were made on two substrates, tile and wood, from an approximate height of 60 cm. Data analysis was done using ImageJ Fiji and IBM SPSS. The results showed that it is possible to differentiate between the heights from which the blood was dripped for drip stains and drip patterns 􀆵􀆐􀅝􀅶􀅐􀀃􀄂􀆌􀄞􀄂􀀃􀄂􀅶􀄚􀀃􀀦􀄞􀆌􀄞􀆚􀍛􀆐􀀃 Diameter. The differences were significant between 50 cm and 100 cm and 50 cm and 150 cm for the tile substrate whereas the differences were significant between 50 cm and 150 cm for the wood substrate. The satellite stain distribution differed depending on height and substrate with the total number of satellite stains increasing as height increased. No significant differences 􀅝􀅶􀀃􀆚􀅚􀄞􀀃􀄂􀆌􀄞􀄂􀀃􀅽􀆌􀀃􀀦􀄞􀆌􀄞􀆚􀍛􀆐􀀃􀀘􀅝􀄂􀅵eter, or distance between bloodstains, were observed between the tile and wood substrates. This information can aid analysts in identifying drip stains, drip patterns and drip trails in their case work as well as determine the approximate height from which the bloodstain dripped.