What is the term for areas without staining where blood should be present?

The term that describes areas without staining where blood should be present is referred to as "voids." In blood pattern analysis, a void occurs when an object blocks the path of blood that would typically have stained an area. This blockage creates a clear impression or absence of blood in an area that would otherwise be expected to show staining due to the trajectory of blood spatter.

Understanding voids is critical in crime scene investigations, as they can help forensic experts determine the positions of individuals and objects during a violent incident. Identifying a void can indicate the presence of a person, giving insight into the dynamics of the event. Other options like stains refer to actual blood markings, impressions pertain to the markings left by an object making contact, and absences would be a more general term without the specific forensic context that "voids" conveys. Thus, the correct term in this context is voids, as they directly signify the absence of blood in areas where it would typically be present.