The definition of evidence is "the means by which disputed facts are proved to be true or untrue in any trial before a court of law or an agency that functions like a court." -Encarta 98
In America no value is assigned to the quantity or form of the evidence. Thus the effectiveness is determined on how convincing the evidence is. The burden of producing evidence is appointed to one side or the other in a court case.
"Rules of admissibility determine which items of evidence judges or juries may be permitted to hear, see or read. Modern codes declare that all "relevant" evidence should be admitted for consideration unless specifically excluded by law". -Encarta 98
Evidence may include: Witnesses, weapons, chemicals in the blood, urine or other bodily secretions, or on the skin, clothing, etc., fingerprints, blood, hair, fibers, skin, semen, DNA fingerprinting, bite marks (only circumstantial), wounds, autopsies, and documents.
Evidence is used to determine whether a death was an accident, suicide, or a homicide by a Medical Examiner. If a gun was involved the Medical Examiner looks for gunpowder residues. This is used to estimate how far away the gun was fired and whether it was fired by the victim or someone else. If a knife was involved the Medical Examiner looks at the wounds to tell if it is a cut (longer than it is deep) and a stab wound (deeper than it is long). He will also look for defense wounds, cuts caused when an intended victim grabs the knife of the assailant in self-defense. Cuts are associated with suicide, because the individual is usually hesitant. If the victim was asphyxiated the Medical Examiner looks for signs of hanging (suicide) or strangulation (homicide). Asphyxiation can be caused by; obstruction of the victim's air passage, compression of the victim's chest, or by the replacement of oxygen in the red blood cells (carbon monoxide poisoning). "In a death involving carbon monoxide poisoning, a closed garage door and no marks on the body are usually taken as an indication of suicide, whereas the presence of tools around the car and grease on the victim's hands points to accidental death. A wound caused by a blow to the head or the absence of carbon monoxide in the blood indicates an attempt to make a homicide look like a suicide". - Encarta 98