Different types of evidence will be collected at a crime scene to help investigators understand what took place. The specific type of crime will also determine what is necessary to prove the guilt of the defendant in a criminal court of law. Crime scene investigation has become very high-tech especially with the use of DNA evidence.
What Was the Crime?
When the police arrive, they will make an initial assessment of what crime took place. The professional crime scene investigators will develop a theory on the crime basically - Who, What, Why, Where and When. Evidence will be collected to assist the government in proving who is guilty of the crime and recreating the crime for a jury.
Categories of Evidence
If there is a corpse, then an outline of tape will be place around it. Pictures will be taken before it is brought to the coroner for a more precise investigation. The initial investigation will look for blood marks, stains, bruises, cuts and the appearance of the clothing. Insect activity can help confirm the time of death.
Pictures will be taken of the overall crime scene. Are there signs of forced entry through a window or door? Is the furniture out-of-place? Are there any wet towels? Are there signs of food preparation? How many place settings are out? Is their half-eaten food or debris in the garbage?
Any potential weapons will be examined for blood or damage. Personal items, like clothing, mail and electronics may be bagged for closer scrutiny back at the crime lab. Documents could help determine a potential motive.
Searching for trace amounts of fluids, hair, fabric and other materials can be the most challenging and fulfilling task. Fingerprints on a weapon, glass or door knob will show who was in the room. Lipstick on a glass or lapel will show the presence of a woman. Paint, glass or wooden fragments can be useful for determining if something was present and removed from the scene. The final assessment is to look for damage caused by the movement of a body or projectile.