ABSTRACT
Biological evidence is found on the body and clothing of the victim or perpetrator and at the scene. Biological evidence is a valuable source in determining physical presence or contact as well as actions within a scene. The DNA of the person may be transferred through shed skin cells or body fluids. Touch DNA refers to an incidental transfer of genetic material when an object is handled, touched, or brushed up against. Biological fluids such as blood, semen, saliva, and urine may be left on the body of the deceased or at the scene. These stains may be either wet or dry, or in some cases pooled. The presence of a stain in the appropriate scene context is sufficient to indicate it is biological. Biological evidence is usually encountered in one of four conditions: dry, wet, liquid and tissue.
