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FORENSIC PATHOLOGY
"We must have the courage to know the causes of death" (Ramsey Clark)
Forensic medicine has been around for years, and is the least difficult area of scientific evidence (in terms of admissibility) because of a rather close relationship that exists between law and medicine. Pathology is the branch of medicine associated with the study of structural changes caused by disease or injury. Forensic pathology simply adds the word "unnatural" or "suspicious" in front of the phrase "disease or injury". There are actually two branches of pathology: anatomic -- which deals with structural alterations of the human body; and clinical -- which deals with laboratory examination of samples removed from the body. Most forensic pathologists are experts in both branches.
To become a forensic pathologist, one must spend at least two years as an intern after graduation from medical school. An additional year of study is expected to prepare for passing the board exam with the American Board of Pathology. Such experts are certified at:
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establishing cause of death
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estimating the time of death
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inferring the type of weapon used
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distinguishing homicide from suicide
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establishing the identity of the deceased
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determining the additive effect of trauma or pre-existing conditions
States either have a CORONER system or a MEDICAL EXAMINER system. Under the coroner system, the coroner is usually an elected official and need not even be a medical doctor, although they should have had at least some medical training. In Texas, for example, the Justice of the Peace is also usually the coroner (who calls inquests and orders lab tests). Coroners are not exempt from civil liability for acts of negligence; medical examiners are.
Medical examiners operate out of centralized offices at the state capital, or else they are part of an inter-county, regional arrangement. They are frequently vested with both law enforcement powers (to hire their own homicide investigators) and quasi-judicial powers (to call inquests and take sworn testimony).
AUTOPSY
The purpose of an autopsy is to observe and make a permanent legal record as soon as possible of the gross and minute anatomical peculiarities of a recently discovered dead body. Autopsies are typically done at a local hospital or at the county morgue, although some are done in private offices or in funeral parlors.
Anatomic examination may be sufficient to establish cause of death if the forensic pathologist has access to other information (such as surrounding circumstances; life history, psychiatric data, and other pertinent patient information). Forensic pathologists also sometimes engage in "psychological autopsies", although these are not all that readily accepted by the legal system. Clinical, or microscopic, examination of organ parts is often necessary to further bolster the forensic pathologist's conclusions, although such examination would be impossible in an exhumation case (or where the family opposed it) since embalming usually thwarts microscopic lab testing.
Forensic pathologists almost always order X-ray examination whenever a firearm is involved. X-rays are also sometimes useful in stab wound and child abuse cases. The examination of organ parts from the body is useful in toxicology cases as well as anytime alcohol or drugs are suspected. The inspection of stomach contents is part of every postmortem exam since it may provide information as to cause of death as well as time of death. Clinical examination also tends to confirm hunches about age, race, sex, height, weight, and general health condition in cases of unidentified remains.
Before getting into autopsy reports and their interpretation, let's take a look at a couple of WAYS IN WHICH INJURIES CAUSE DEATH:
ASPHYXIA
All asphyxia cases involve insufficient amounts of oxygen reaching the brain or essential organs of the body, and there are many ways in which asphyxia occurs. First of all, there are certain natural diseases which shut down the respiratory system; e.g., emphysema, pneumonia, flu, asthma, larynx disorders, etc. Then, there are three (3) common criminal means: strangulation, drowning, and smothering.
STRANGULATION may be homicidal, suicidal, or accidental. The homicidal variety is usually done either manually (brute force choking around neck) or by ligature (using a rope, wire, or garrote). In hanging, the victim dies from the pressure of body weight or the neck gets broken. All cases of strangulation are characterized by the following:
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intensive heart congestion (enlarged heart; right side ventricle)
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venous engorgement (enlarged veins above point of injury)
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cyanosis (blue discoloration of lips and fingertips)
DROWNING results from the inhalation of water which causes choking which in turn causes the rapid formation of mucus in the throat and windpipe. The spread of this thick, foamy mucus is actually what ceases respiration, and victims (even in some drug overdose cases) will be identifiable by the presence of a "foam cone" covering the mouth and nostrils. In some cases, "dry drowning" occurs because shock causes enlargement of the larynx, and no fluids will be found in the lungs or stomach as is typical of your more common drowning where lots of liquid (as well as marine life) is often present. The classic drowning goes through five stages:
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surprise (person is stunned and inhales water)
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holding breath (person tries to hold breath while struggling)
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pink foam (person inhales deeply & pink foam is expelled)
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respiratory arrest (thoracic movement and pupils dilate)
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final struggle (3-4 quick attempts to breath and find air)
SMOTHERING occurs when airways are closed by an obstructing object, such as a pillow or blanket. If a soft object has been used, the body will show no visible signs of trauma, but often there are small, discernible contusions or lacerations on the inner lips. Cyanosis may or may not be present, but there is usually what is called petechial hemorrhage -- small, pin-point blotches or dark red spots on the face, typically around the area of the eyes.
WOUNDS
Generally, all wounds fall into the categories of bullet wounds, stab wounds, blunt force wounds, rape wounds, poisoning (considered a toxicological type of wound), burn wounds, and traffic fatality wounds. Forensic pathologists attempt to reconstruct what happened from wound analysis as well as determine whether self-defense occurred and whether or not the wound was received prior or after death. In gunshot cases, they provide valuable ballistics information. Unless the object causing the wound hits a vital organ, the most common mechanism of death is shock -- the body simply shuts down in a more or less conscious realization that the damage (to the circulatory system) is too great for the body to repair itself. This is the much more typical pathway to death than the process of bleeding to death, but it depends on the weapon. Bullets usually shock a person to death; knives usually cause a person to bleed to death. Both internal and external hemorrhage are always present with wounds.
BULLET WOUNDS follow the principles of physics. The greater the energy of the missile at the moment of impact, the greater the tissue destruction. The striking energy of a projectile is the product of its mass or weight multiplied by the square of its velocity. Because it is squared, velocity is the most important factor, not the size or caliber of the bullet. High-impact, or magnum, rounds have greater destructive power to cause shock leading to death. Hollow points, or other fragmenting ammo are designed to spread out and hit vital organs. From a death standpoint, however, high-powered rifles kill much faster than either handguns or shotguns. Many forensic pathologists are also experts at firearms identification and the science of ballistics.
Entry and exit wound areas are important to look at. Because a bullet is spinning as it hits the body, it perforates the surface of the skin quite efficiently. Therefore, the entry area is usually smaller than the exit area, and it's often possible to determine the caliber from the entry wound. Exit wounds are usually larger than entry wounds, although sometimes the bullet ricochets inside the body (owing to different tissue strength) or travels a path which is not a straight line (non-axial flight).
Powder burns (there's always some scorching or burning of the skin) are examined to determine distance and direction of fire. The degree of scorching usually tells the distance, and the "contusion ring" (abrasion collar) around the bullet wound usually indicates the angle (round is straight on; oval is at an angle). The exact identification of any powder residue is not a job for the forensic pathologist, but the province of a specialist in explosives chemistry.
STAB WOUNDS include slash wounds and incision wounds. Slash wounds tend to look like bullet wounds that only graze the surface of the skin. Other types of slash wounds are called "hesitation marks" commonly found in suicide cases. They are typically rectangular in shape; i.e., their cuts are as wide and they are long. Incision wounds, on the other hand, always have lengths greater than their depth, and you'll easily notice that a greater amount of subsurface tissue is exposed in an almost oval fashion. Another type of wound is the puncture wound (sometimes called a stab or "shive" wound) which has no geometric shape (except perhaps circular) and is most distinguishable by its clean-cut edges.
In determining if the wound was pre- or post-mortem, the general rule is that a pre-mortem wound gapes and bleeds profusely while a postmortem wound does not. Wounds where the attacker not only stuck the victim with something, but twisted the object, cause the most shock and speed up the death process whereas blood vessel hemorrhage or bleeding to death are the most common pathways to death. Generally, the depth of the wound is not all that important.
BLUNT FORCE trauma results from clubbing, kicking, or hitting the victims. The blow produces a crushing effect on the human body, resulting in contusions, abrasions, lacerations, fractures, or rupture of vital organs. Red-blue contusions are always present, but this varies by the weight of the individual (obese people bruise easier than lean people).
Brain contusions are especially difficult to analyze. The general rule is that trauma will be most severe on the opposite side of impact. This is because the brain floats around inside the head, but there may be what are called contrecoups where the pathway to brain trauma has to be reconstructed. Death results rapidly whenever a skull fracture is involved.
Wounds to the body area usually take longer to cause death, sometimes days. However, sometimes death occurs in a matter of hours after wounds to the body. This is due to the process of pulmonary embolism (where blood clots travel to the brain). Some resuscitative (first aid) measures cause more harm than good with blunt force injuries.
RAPE WOUNDS involves examination of the genital area for signs of tearing, scratching, or bruising. Female victims are always checked for whether or not they were virgins via looking at the hymen, if any. The existence of venereal disease and/or pregnancy will also be determined. Foreign pubic hair, blood stains, and seminal stains are also collected. In cases where the assailant ejaculated, DNA typing is done to help identify who deposited the sperm.
POISONING is usually determinable by looking at discolorations on the body. Cherry-red lividity is usually a sign of carbon monoxide poisoning, for example. Other toxins give off unusual odors. Certainty of diagnosis, however, requires toxicological confirmation. Samples must be taken of the stomach, vomitus, kidney, lungs, and liver.
BURN wounds may be caused by heat, a chemical, or electricity. Fire victims often are found in a "pugilistic" position with clenched fists, resembling the pose of a boxer. Heat generally causes the protein in the body to contract. Blood and lung samples are often taken for various reasons.
TRAFFIC FATALITIES are often analyzed to determine if the victim was the driver, a passenger, or a pedestrian. Motorcycle injuries are the most severe, especially in the head area (if no helmet is worn). The drivers of automobiles will normally have a circular impression in their chest area. Passengers will normally have extensive knee and spinal injuries. Pedestrians will normally have extensive ankle injuries or injury anywhere near the lower one-third of the body (called "bumper fractures"). Generally, the lower on the legs the bumper fractures, the more likely it can be said the driver attempted to brake or slow down. Run-over injuries are quite different, and distinguishable by the amount of compressed tissue damage. Forensic pathologists often check for blood alcohol and drug levels in all cases involving traffic fatalities. This is for reasons of determining negligence under civil law.
AUTOPSY REPORTS & THEIR INTERPRETATION
The typical autopsy report is a two-pane sheet which looks like the following:
| PATHOLOGICAL DIAGNOSIS: Cardiovascular: Heart normal, no signs of hypertrophy, valvular, or congenital abnormalities. Coronary arteries normal and distributed. No right coronary predominance. Myocardium, no evidence of trauma, fibrosis, or inflammation. Aorta, mild arteriosclerosis. Respiratory: Larynx, trachea, and bronchi show no signs of trauma or obstruction. Lungs, pulmonary congestion and edema present; upper lobes have atypical obstruction. Liver: No evidence of trauma or inflammation. |  |
| Cause of Death: Perforating Wound to Head: Peritoneum: Intact, smooth Heart: 415 gm. No gross evidence of trauma, some slight right coronary predominance. Lungs: Right 640 gm; Left 490 gm; all areas free of obstruction except apex of upper lobes which show evidence of scarring. Liver: 1840 gm; Intact, some congestion Brain: 1575 mg; Perforating gunshot wound, entrance in right superior to ear, oval wound 5/8" by 1/2" with rim of powder debris. Linear track extends backward and to left, passing thru parietal lobe and left cerebrum, exiting near left parietal bone. Multiple fractures on exit side. | |
INTERPRETATION
The general manner in which the law interprets autopsy reports is as follows. Note that the report is interpreted in terms of a 4-stage model. In some jurisdictions (and in all civil trials) the final part of the model ("manner of death") is admissible but only as an issue which is the province of the jury (fact finder) to decide.
The "contributing cause" is usually a pre-existing illness or condition. An example would be pneumonia or asthma, if the victim had either of those conditions. They could conceivably be the real cause of death.
The "mechanism" part of the model is usually anything expressible only in medical jargon. An example would be words like "lung sacs became obstructed and could no longer transport oxygen".
The "immediate cause" section usually gets at the cause of death. It can be expressed in medical jargon, such as "asphyxia", "contusion", etc., or it can be expressed in laymen's terms such as "perforating gunshot wound to the head". Asphyxia or wound are the most common terms used, however.
The "manner of death" records whether the forensic pathologist thinks the death is a suicide, a homicide, accidental, natural, or unknown. The general rule is that manner equals mechanism plus immediate cause, but there are other general rules also. If the mechanism is undetermined, the death must be ruled as "unknown manner". This occurs in some poisoning cases and other strange phenomenon (like spontaneous combustion). If the immediate cause simply aggravated a significant pre-existing condition (contributing cause), the death must be ruled "natural". Most traffic fatalities are ruled "accidental". All suicides are ruled as "homicides" if another person (other than decedent) is involved in the immediate cause of death.
INTERNET RESOURCES
How an Autopsy is Done (and Internet Autopsy Links)
Lido.com: Forensic Medicine Images for Trial Exhibits
National Association of Medical Examiners
Reddy's Forensic Pathology Links
PRINTED RESOURCES
Dana, S. & DiMaio, V. (1999). Handbook of forensic pathology. Boca Raton, FL: CRC Press.
DiMaio, V. & DiMaio, D. (2002). Forensic pathology, 2e. Boca Raton, FL: CRC Press.
Emsley, J. (2005). The elements of murder: A history of poison. NY: Oxford Univ. Press.
Moenssens, Inbau, & Starrs. (1986) Scientific evidence in criminal cases, 3rd ed. Mineola, NY: Foundation Press.
Spitz, W. (1993) (ed.) Medicolegal investigation of death: Guidelines for the application of pathology to crime investigtion. Springfield: Charles Thomas.
Last updated: Mar 6, 2008
Not an official webpage of APSU, copyright restrictions apply, see Megalinks in Criminal Justice
O'Connor, T. (Date of Last Update at bottom of page). In Part of web cited (Windows name for file at top of browser), MegaLinks in Criminal Justice. Retrieved from http://www.apsu.edu/oconnort/rest of URL accessed on today's date.
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