Blood is among the most common forms of evidence found at scenes of violent and brutal crimes. All suspected blood—liquid or dried, animal or human—present suggests a relationship to the offense or persons involved in a crime. Blood may be found in trace amounts, puddles, spatters, smears, or droplets. Blood samples may be collected from suspects and victims for examination and comparison. Blood evidence can help narrow a group of suspects, support identification of a suspect, and even guide the reconstruction of a crime.