many suicidal and accidental deaths result from carbon monoxide poisoning. A common mode of
suicide is for the victim to connect the exhaust of an automobile into the vehicle passenger
compartment, allowing the victim to inhale the exhaust emissions until unconsciousness and
eventual death occurs. Many accidental deaths occur due to faulty exhaust systems in vehicles,
allowing exhaust emissions to seep into the passenger compartment, or from malfunctioning
heating devices in living quarters. Note that alcohol, barbiturates, sedatives, and numerous other
drugs are factors that increase the toxic effect of acute carbon monoxide poisoning. Investigation in
these cases should include inspection of the device suspected of malfunctioning by an expert and a
thorough examination of the death scene by the investigating agent. A telltale sign of carbon
monoxide poisoning is a bright cherry red discoloration of the skin, the blood, and the livor mortis
(discussed later in this chapter). The fingernails are also involved in providing telltale signs of
deaths associated with carbon monoxide poisoning and are usually discolored purple. However,
cyanide poisoning and exposure of the dead body to a cold and moist environment may cause
redness indistinguishable from that due to carbon monoxide. Likewise, with lower concentration
the color may go unnoticed. An autopsy generally establishes that death resulted from carbon
monoxide poisoning in these cases.
30-9.7. Blunt Force Injuries. Blunt force injuries are the result of falls, collisions, or blows with
blunt instruments or surfaces. Wounds produced by blunt force are generally characterized by
tearing, shearing, or crushing of tissue, bone, or internal organs. Extensive bleeding into adjacent
soft tissue is the general rule. These injuries may or may not indicate a struggle and must be
carefully examined and interpreted by the agent and the pathologist. The three basic types of blunt
force injuries are detailed below:
a. Contusion (Bruise). A contusion signifies hemorrhage into the skin or subcutaneous tissue or
both. It results from a blow or compression that crushes the soft tissue and ruptures blood vessels
but does not break the skin. The presence of contusions may indicate the victim engaged in a
struggle. However, the investigating agent should be cognizant that not all application of blunt
force causes a contusion and contusions may be inflicted on a body after death. Additionally, the
instrument used to inflict the contusion may be identified from the injury itself. Often the pattern of
the injury mirrors the instrument (e.g., belt buckle, length of wire, nightstick, etc.) and recognition
of the pattern may help in reconstruction of the circumstances of injury. Bruises change color over
time in a general progression and generally, the color of a bruise changes from light bluish-red to
dark purple, green, yellow, and then brown. This change proceeds from the periphery of the bruise
toward its center and vice versa. Thus, a discolored bruise with pale center is likely to be at least
several days old, depending on a number of factors. Microscopic examination for aging of a bruise
is generally recommended for a more accurate evaluation.
b. Laceration. A laceration is a tear produced by a blunt force trauma. The force and its
direction determine the appearance, depth, and associated injury. A laceration may result from a
perpendicular blow with a relatively broad object (such as a hammer or by falling onto a hard
surface) or by a glancing blow, tearing only the skin. A laceration may be external, with tearing of
the skin and tissues, or internal, where organs are ruptured, split, or fragmented. A laceration on the
external portion of the victim's body should not be confused with an incised wound as a laceration
has the following characteristics: abraded margins, ragged edges, and bridging of blood vessels,
nerves and connective tissue.