For the patrol officers who are first on the crime scene, the principal instruction is not to touch or change anything at the crime scene. Should the victim be alive at the time of an officer's arrival, an ambulance should be immediately called, and one officer should accompany the victim to the hospital to obtain a statement from the victim en route if possible. Another officer should remain at the crime scene to ensure it is not contaminated and to identify witnesses and possible suspects. Before the victim is removed for treatment, notes should be taken and sketches made about the position of the body as well as other observations at the crime scene. Any handling of objects at the crime scene should be left for investigators. Outdoor crime scenes require special procedures, particularly to ensure that evidence is not changed or erased by weather conditions. The investigation itself should make generous use of photographs before anything is altered at the crime scene. In handling the body, care should be taken to ensure that any fibers or other materials on the body are not lost in transport. The autopsy should be viewed as a major source of information about the cause and manner of death. Preservation of any evidence associated with the victim's clothing is very important. Closeup photographs of wounds should be taken with a ruler placed in the picture to indicate scale. Head and pubic hairs samples are collected as the nature of the case requires. If a rape is suspected, vaginal smears should be obtained by the medical examiner to be forwarded to the lab. Ink elimination finger and palm prints of the deceased should be taken at the morgue; and hands should be swabbed for firearms residue before fingerprinting.