This document discusses several methods for determining blood types from bloodstains, including the Lattes test, absorption-elution assay, mixed agglutination technique, and absorption-inhibition test. The Lattes test involves incubating blood crusts with cell suspensions to look for agglutination under a microscope. The absorption-elution assay detects antigens in dried bloodstains by binding antibodies at low temperatures, then eluting and identifying the antibodies. The mixed agglutination technique uses known antiserum and indicator cells to look for cell attachment to stains. The absorption-inhibition test employs titered antiserum and measures its ability to agglutinate cells after exposure to a stain, indicating the presence