What defines transfer stains?

Transfer stains are specifically defined as marks created when a wet, blood-covered object comes into contact with a surface and then deposits some of its blood onto that surface. This occurs when blood on an object is inadvertently transferred to another location through direct contact. Recognizing transfer stains is crucial in forensic analysis as they can provide insight into the movements and actions of individuals during a violent event.

In contrast, options discussing blood projections, severed arteries, or expelled blood do not encapsulate the essence of transfer stains. Blood projecting through the air refers to the dynamics of spatter, blood from a severed artery emphasizes the source and method of blood loss from a wound, and blood expelled from the lungs typically pertains to the processes associated with certain injuries or medical conditions. Each of these focuses on different aspects of blood evidence rather than the direct contact and transfer involved in creating transfer stains.