Final answer:
When a victim is stabbed in the chest and coughs, blood can be expelled from the wound, creating an expiratory blood pattern. The assailant may have a cast-off blood pattern on their face due to the expelled blood from the victim's coughing.
Step-by-step explanation:
When a victim is stabbed in the chest but not directly in the heart, coughing may cause blood to be expelled from the wound. This blood can generate a type of blood spatter known as an expiratory blood pattern. An expiratory blood pattern occurs when blood is propelled out of the body due to forceful expiration, such as coughing or exhaling.
When the victim coughs in the assailant's face, the expelled blood can create a cast-off blood pattern on the assailant's face. Cast-off blood patterns are created when a bloody object (in this case, the victim's mouth) swings through the air and casts off blood droplets onto a surface (the assailant's face). The pattern can vary depending on the direction, force, and angle of the swing, as well as other factors.