1. Bloodstain

2. Direction of Travel
When a droplet of blood strikes a surface perpendicular (90 degrees) the resulting bloodstain will be circular thus the length and width of the stain will be equal. However, when blood strikes a surface at an angle less than 90 degrees the stain will be elongated or have a teardrop shape. It is readily apparent to the trained eye of the homicide detective. For instance the teardrop shaped stains with pointed end always points in the direction of travel.

3. BLOODSTAIN EVIDENCE AT THE SCENE
Blood is present in most crimes scene involving violence and therefore presents the investigator with additional information to determine the sequence of events, which may have taken place between the victim and the assailant. Bloodstain patterns at the scene or from the clothing of principals in a case can be used to confirm or refute assumptions concerning events and their sequence. In addition, bloodstain patterns can illustrate the position of the victim, such as standing, sitting, or lying.

4. Conclusion
Bloodstain Pattern Analysis (BPA) is a discipline, which requires formal training coupled with years of practical experience. The discipline of bloodstain pattern analysis considers the location, shape, size, distribution and other physical characteristics of the bloodstains in the scene. The Scientific Working Group on Bloodstain Pattern Analysis entitled (SWGSTAIN) was created in 2002 and has established many of the current protocols.