Rape investigation teams comprise two officers with distinct duties at the crime scene. One officer should provide psychological first aid to the victim while the other concerns himself with evidence collection and preservation. In dealing with the victim, it is emphasized that she be informed of what the officers are doing and why, and that they obtain her permission before proceeding with their investigative tasks. Information derived from the victim includes time of the offense, nature and source of any weapon used, exact description of the offender, and prior offender-victim relationship. Crime scene evidence collection requires noting signs of struggle and quickly gathering, packaging, and labeling soiled bedding, clothing, and other items that may contain perishable evidence in the form of body fluid traces. Maintaining the chain of evidence is critical. The interviewing officer should accompany the victim to the hospital, where she should be received in a private waiting room. It is the officer's responsibility to specify all needed evidence of the medical examiner and supervise the victim's signing of consent forms. The officer should remain outside the examining room and deal with matters contingent to the case, such as distraught parents arriving at the hospital to be with their daughter. Police should receive from the hospital evidence obtained from the victim's body (blood samples, saliva, hair, finger nail cuttings, vaginal swabs, etc.), properly labeled and with the victim's signature on all specimen containers. This type of evidence must then be turned in for immediate analysis.