What is meant by "swipe or smear" in blood analysis?

The term "swipe or smear" in blood analysis refers specifically to the transfer of blood onto a surface, which may inadvertently contaminate what was previously a clean surface. When blood is smeared, it typically occurs when an object or body part comes into direct contact with a blood stain, leading to a dispersal of the blood onto another area. This can be crucial evidence in a forensic investigation as it can show the movement of a suspect or victim, or the interaction at a crime scene. Recognizing this type of evidence helps investigators understand the dynamics of how blood was transferred during the incident, potentially offering insights into the sequence of events.