It also aims to help prosecutors and defense attorneys understand the significance of blood for the preparation of their cases that involve the interpretation of bloodstain evidence. Medical and physiological facts concerning blood that contribute to the complete examination of blood evidence at the crime scene are explained. Consideration is also given to the clotting and during time of blood with respect to time intervals and various surface textures. A review of the volume of blood flow through different body areas is also presented. The proper techniques of blood collection at crime scenes are emphasized, including the importance of good photography and documentation of the evidence. An overview of blood identification is provided, with emphasis on preliminary testing at the scene. The individualization of blood and the emergence of deoxyribonucleic acid typing are also explained. Special problems addressed include blood diluted by snow or water and blood-flow patterns relative to the victim's final position at a crime scene. Newer techniques that are the subject of research and experimentation are also outlined. The potential exposure of medicolegal personnel to the AIDS virus during crime scene examination, postmortem procedures, and examination is explained, with emphasis on precautions to be taken. Case presentations in which bloodstain evidence and the interpretation of bloodstain patterns were significant to the ultimate outcome of the investigations are included. Figures, tables, photographs, chapter reference lists, glossary, computer program for bloodstain pattern interpretation, index, and international bibliography of more than 500 references. (Author summary modified)