Strangulation is asphyxiation arising from compression on the neck. It can be done manually or with any ligature like a binder, a rope, a necktie. Strangulation may also be caused by hard blows made to the neck. Punches or chops that are aimed to strike at the throat may cause damage to the larynx, which would be followed by suffocation.
Manual strangulation is a homicide. A person cannot strangle himself with his own bare hands by virtue of the fact that when he loses consciousness from asphyxiation, his hands will relax and his breathing will resume. In manual strangulation, the attacker's fingernails will often make small tell-tale bruises or marks on the neck. However, the marks on the neck will unfortunately not show the direction from which the victim was attacked. In addition, fingernails also vary in size and shape. Another sign of manual strangulation is hemorrhaging in the throat area, and this can normally be seen in an autopsy. Sometimes a fracture of the hyoid bone (a U-shaped bone at the base of the tongue) is also found.
Strangulation by ligature may be homicidal or suicidal. It is a fairly common form of suicide, but it is a rare form of homicide. The ligature often is made from something handy at the scene. Pieces of loose clothing like shirts, neckties, belts and hosehold appliances like electrical cords can often be used. Strangulation by a garrote of rope or wire sometimes is used in homicidal strangulation, but it is not seen very often. Close inspection of the marks left on the skin may show the type of garrote used.
When investigating crime scene involving strangulation, one should normally search the scene and the victim for signs of struggle. One should also obtain fingernail scrapings. In addition, one should check the victim's body for signs of defense wounds as the presence of such wounds may suggest homicide. Finally, one should look for the presence of hesitation marks which hints at attempted suicide by other means before ruling it a homicide.