Cast-Off Stains
What are cast-off stains? Cast-off stains are the result of blood which has been flung off some type of object or weapon. These stains will normally appear linear with variations in length and may produce an arching effect. The width of the stain trails depend on factors such as the object used and the amount (volume) of blood that may have adhered to it. The object or weapon used may present a larger or smaller surface to which blood may accumulate, thus narrowing down the possibilities of objects used for the expert. A knife for example with its small tip would normally produce smaller stains as compared with lets say a sledge hammer. The bloodstain expert can look at these stains and determine in some cases the minimum number of blows struck and/or inflicted. A few of the ways they do this is by looking at the directionality of the stains and counting the linear trails present. Cast-off stains can also reveal whether or not a subject is left or right handed. Remember, the tails of the stains point in the direction of travel (unless a satellite stain and/or wave cast-off stain). When determining how many swings have occurred you must pay attention to the directionality of the stains. Some linear trails will be created on the upswing as well as the downswing. Additionally, it appears to be common place to add 1 blow to the total counted, as the first blow would not normally accumulate enough blood to be flung off. In any case the number assigned should be a conservative one.
Cast-off by flicking finger dipped in blood. Cast-off with knife covered in blood.
Frontal cast-off from a hatchet. Rearward cast-off from a hatchet by alternating hands.
(Notice the X it makes by switching hands. This may help
in determining which hand was used.)