Blood Spatter Catagories Continued

Transfer/Contact bloodstains A transfer or contact stain is produced when an object with blood comes in contact with an object or surface that does not have blood. It may be possible to discern the object that left the blood impression. Wipe Pattern – A bloodstain pattern created when an object moves through an existing stain, removing and/or altering its appearance. Swipe Pattern – The transfer of blood from a moving source onto an unstained surface. Direction of travel may be determined by the feathered edge. As indicated above, there are other terms currently used in BPA and different ways of classifying bloodstain patterns. For example there is a debate over the misnomer of the LVIS, MVIS, and HVIS as it relates to the physical term ‘’velocity’’. A sub-committee of the SWGSTAIN has been tasked with addressing the terminology issues and develop a taxonomy for bloodstain patterns.

Low velocity impact spatter Low velocity impact spatter (LVIS) is generally produced when objects traveling less than 1.5 m/s come in contact with a blood source. The preponderance of stains is generally larger than 3 mm in diameter.

Medium velocity impact spatter Medium velocity impact spatter (MVIS) is generally produced when objects traveling between 1.5 m/s and 7.5 m/s come in contact with a blood source. The preponderance of stains is generally between 1 mm and 3 mm in diameter. Mechanisms that could produce this type of pattern include blunt force trauma or cutting/stabbing actions.

High velocity impact spatter High velocity impact spatter (HVIS) is generally produced when objects traveling greater than 30 m/s come in contact with a blood source. The preponderance of stains is generally smaller than 1 mm in diameter. This pattern often has a mist-like appearance. High velocity patterns may be created by gunshots or explosives, but may also be caused by industrial machinery, coughing, or sneezing.