1. _In Hanging and Strangulation._--The mark due to pressure of the cord on the neck in hanging runs obliquely round the neck; in strangulation, the mark encircles the neck. The mark is frequently interrupted, and may present very varied appearances in different parts of the neck. The mark of the knot may be found under the chin. 2. _In Throttling._--The pressure exerted on the throat of the deceased by the fingers of his assailant may leave marks which may point to the means used to cause death. 3. _In other Cases of Death by Violence._--The impression made by the weapon used may lead to the identification of the murderer. The marks left by the wards of a large door-key once led to the identification of the assailant. CHAPTER VIII SUFFOCATION, HANGING, STRANGLING, AND THROTTLING SUFFOCATION Death from suffocation is said to result from any impediment to the respiration which does not act by compressing the larynx or trachea. Suffocation may therefore be caused by pressure on the chest, as in persons crushed in a crowd. It may also be due to the respiration of certain gases, or to the presence of pulverulent substances in the air, which act by choking up the air-passages. Imprisonment in any confined space may cause death from suffocation, and abscesses bursting into the trachea, or vomiting matters in drunken persons lodging in the windpipe, may be attended with a like result. Pressure on the umbilical cord whilst the child is in the maternal passages causes death from suffocation.