Drying Processes in the Formation of Bloodstains at Crime Scenes

Dried blood stains are of value in reconstructing the sequence of events at crime scenes. Valuable information is contained in the size, shape and pattern of stains. This chapter describes the spreading, splashing and drying process in small stains and large pools. Drying proceeds through multiple stages as the red blood cells and other non-volatile constituents concentrate. Clotting and/or serum separation can occur. Drying on nonporous surfaces proceeds through well-understood stages featuring red blood cell motion on internal currents, gelation, further desiccation and sometimes cracking of the solidified stains. Drying on porous surfaces is less well understood. Fabrics are particularly important forensically. Recent work to understand the relationship between fabric structure and the shape and size of dried stains is described.