Viewers are advised to notify the police and the victim-witness crisis center when a rape victim seeks treatment from emergency room personnel. If possible, a trained rape victim counselor should be called to comfort and advise the victim. The doctor in charge informs the victim that staff will both treat her for any injuries suffered from the attack and also collect physical evidence to aid in the police investigation. The victim is not obligated to submit to a medical exam for evidence, but the doctor should encourage it, since the evidence cannot be obtained at a later time should she change her mind about cooperating in the investigation. A relative, friend, or counselor should be encouraged to remain during the medical exam. The exam includes the taking of a medical history, a physical exam to determine the extent of any injuries and the precise nature of the attack, and a pelvic exam. Samples of head and pubic hair should also be obtained, along with any saliva, seminal remnants, and scrapings from under the victim's fingernails. The victim's clothing should be carefully preserved, along with the other evidence obtained. Each item of evidence should be clearly marked and safely stored awaiting police pickup. Procedures for identifying the chain of evidence custody must also be followed.