Which type of evidence is commonly recovered from crime scenes, including blood, saliva, and other bodily fluids?

Biological evidence is a key category of physical evidence that includes any evidence derived from a biological source. This can encompass substances such as blood, saliva, urine, semen, and other bodily fluids. These types of evidence are crucial in forensic investigations as they can provide vital information regarding a suspect or victim. For instance, DNA analysis from blood or saliva can help identify individuals involved in a crime or confirm their presence at a crime scene.

Biological evidence plays a significant role in connecting individuals to a crime scene or establishing a victim's identity. It serves not only to link potential suspects to a crime but also to exonerate those wrongfully accused. The ability to analyze biological evidence has revolutionized forensic science, making it a cornerstone in criminal investigations.

The other types of evidence mentioned serve different purposes. Physical evidence refers to tangible items that can be collected and analyzed, but it doesn't specifically denote biological materials. Forensic evidence is a more general term that encompasses all types of evidence used in court, not limited to biological materials. Circumstantial evidence refers to evidence that requires an inference to connect it to a conclusion, such as a witness seeing someone near a crime scene, which differs fundamentally from the direct nature of biological evidence.