The spatter pattern found on the west wall was caused by a gunshot wound inflicted on the victim's head.
The blood spatter pattern was created as a result of the arterial spurt produced by the beating of the heart. Arterial blood spatter is created by a pulsating, pressurized blood flow, which ejects blood droplets in a continuous series of spurts. Because arterial blood spatter is produced by a beating heart, the resulting pattern is distinct from that created by the passive dripping of blood from a body, which is influenced by gravity. The height of the origin of the blood source may also be determined by the spatter pattern of arterial blood. The greater the height of the source, the more elongated the bloodstains will be on the surface, as the droplets will be more horizontally dispersed by the force of gravity. In conclusion, the spatter pattern found on the west wall was created by arterial blood spatter caused by the gunshot wound to the victim's head.