ABSTRACT
When a bloodstain pattern has been identified as spatter based on the size, shape, or distribution of the stains, it is frequently possible to further classify the pattern as impact spatter (Figure 7.1). Impact spatter results from an object directly striking a source of exposed blood. The resultant stains may range in size from 0.01 mm to 3 to 4 mm or larger in diameter. Further analysis is required to associate the spatter pattern with beating, stabbing, gunshot, power tool, or explosive events. The identification of impact spatter is case driven in that the size of the stains is not the deciding factor in forming that conclusion. This determination requires assimilation of specific case information pertaining to the assessment of the scene and location of the stains as well as knowledge of the nature of the injuries sustained by the victim(s). If the victim was removed from the scene to another location by the assailant, further caution is advised in making specific determinations. It is important to consider all other mechanisms that are capable of producing bloodstains in a similar size range. There is considerable overlap of stain sizes between impact spatter and mechanisms such as satellite spatter and some projected mechanisms. Some of these mechanisms are nonviolent in nature and not directly associated with the actual infliction of injuries to the victim. Blows administered to a victim with blunt instruments (fists, club, hammer, rock, golf club), as well as with sharp objects such as knives and axes, may produce impact spatter that overlaps the size range of spatters observed in many gunshot cases. When spattered blood is present on clothing and footwear, it is important to obtain the history of this evidence as to when and where the items were collected from a victim or suspect. It is often claimed by suspects that they found the victim, shook them, or attempted cardiopulmonary resuscitation (CPR) or some other activity that may produce small spatters on their clothing.
