Lessons in Forensic Medicine for Criminal Cases
Classification of Injuries in Forensic Medicine:
Injuries can be classified based on the tools used to cause them as follows:
First: Contusion Injuries
These occur as a result of blunt instruments. They involve a separation of the skin, underlying tissues, organs, muscles, and bones due to the use of rough, blunt objects like sticks and similar items.
Contusions can also refer to tears or rips in the skin caused by sharp objects like metal or rocks, and they are common in car accidents. These injuries often come with bone fractures and damage to internal organs. They are divided into:
Abrasions: These are surface wounds caused by friction with a rough, blunt object. They heal over time. They are of several types: scratches, friction abrasions, natural, pressure, and bite marks. The forensic importance of abrasions lies in their indication of violence or exposure to violence, and they can also point to the type of crime or weapon used.
Bruises: These are caused by blunt force trauma, like being hit with sticks or kicked, or from pressure from objects falling onto the body. Bruises result from the tearing of blood vessels at the injury site, causing subcutaneous bleeding. The shape of the bruise often corresponds to the shape of the instrument causing it. For example, a kick bruise is usually curved, while a stick bruise is long and narrow.
Lacerated Wound: This refers to a wound with severe tearing of the edges and significant fragmentation with bleeding.
Crush Injury: This is a laceration resulting from a moving object pressing against part of the body, often accompanied by shattered bones beneath it.
Mutilating Injury: This usually occurs in factories or with industrial machinery when a moving conveyor or similar equipment causes severe, often amputative, injuries to body parts like the arms.
Cutting Injury: A laceration caused by a heavy tool with a sharp edge, such as an axe or cleaver.
Second: Incised Wounds
Incised wounds are caused by sharp objects like knives. They occur when an object with a sharp edge makes a cut in the skin or tissues. These wounds are often found on the neck and extremities.
Characteristics of an incised wound:
- The edges are regular with sharp angles.
- The base is clean, and the bleeding is usually severe.
- Hair is cut sharply, and clothing is torn.
- The length of the wound is greater than its depth.
Forensic and Investigative Signs in Incised Wounds:
Criminal cases: There are signs of violence and resistance, such as bruises or abrasions. There may also be defensive wounds on the victim’s arms, multiple wounds, and their relation to the cause of death.
Suicidal cases: It should be evaluated whether the deceased could have inflicted the wounds on themselves, whether the weapon used is consistent with this, and whether the wounds are potentially fatal or harmful.
Accidental cases: These occur most often due to accidents like falls, collisions, or injuries involving sharp tools during work.
Fabricated cases: These wounds are often self-inflicted to deceive others or exonerate oneself from a particular crime. The superficiality and location of such wounds often reveal their deceptive nature.
Third: Stab Wounds
These wounds are caused by stabbing with a pointed sharp object, like a knife. They are characterized by sharp edges, and the wound depth is greater than its length. The wound has sharp, angular edges from the knife blade.
Types of Stab Wounds:
Criminal Injury: Most stab wounds are criminal in nature and typically occur in lethal areas like the chest and abdomen.
Suicidal Injury: These are very rare and usually found in the lower chest, near the heart. Any stab wound outside this area should be treated with suspicion, as a single stab wound is usually fatal.
Accidental Injury: These are extremely rare, occurring when a person falls onto a pointed object.
Forensic Lessons - Detailed Information on Wounds:
Wounds are defined as tearing or breaking of tissues, and can be:
External: These injuries involve tearing the skin and tissues beneath it, often caused by sharp objects.
Internal: These include fractures or injuries to internal tissues or organs.
Types of Wounds:
Abrasions: These are superficial injuries that affect the outer layer of the skin, often caused by contact with hard, rough objects. For example, injuries from car accidents or bites. Fresh abrasions are red, while post-mortem abrasions may dry out and harden.
Bruises: Medically, these are caused by blood flowing into tissues after blood vessels are torn. They typically appear in a round shape, raised from the skin, and are usually larger than the object causing them. Tools that cause bruises include whips, sticks, belts, chains, and fists.
Tear Wounds: These injuries are caused by tearing of skin tissues, creating irregular, jagged wounds. They often result from accidents or blunt trauma and are characterized by uneven edges.
Incised Wounds: These are caused by sharp tools like blades or knives. The wound is linear and longer than it is deep, and it typically involves bleeding due to the damage to blood vessels.
Stab Wounds: These are caused by sharp, pointed objects like knives. The wound is deeper than its length, and it is often characterized by two sharp angles at the entry site.
The Difference Between Hanging, Strangulation with a Rope, and Manual Strangulation: A Forensic Perspective
Asphyxia:
Asphyxia is the cessation or failure of breathing, resulting in a lack of oxygen supply to the body tissues, especially the brain. The brain cells are extremely sensitive to oxygen deprivation, leading to loss of consciousness within seconds of the cessation of breathing. These cells die after five minutes. The heart stops immediately, and death occurs due to asphyxia.
Conditions Leading to Asphyxia:
Oxygen deprivation can occur due to a lack of oxygen in the inhaled air, or from an obstruction or injury to the respiratory system. Many situations can lead to asphyxia, including the following:
Conditions affecting the airways leading to the lungs:
- Airway obstruction due to the tongue falling back in an unconscious person, or due to food, vomit, or other foreign materials in the airway.
- Swelling of the tissues in the throat due to burns from hot liquids, insect stings, or infection.
- The presence of liquid in the airways.
- Compression of the trachea (windpipe) due to hanging or strangulation.
- Chest compression due to soil or sand collapse, crushing by a wall or barrier, or pressure from a crowd of people.
- Lung injury.
- Chest wall injury.
- Seizures preventing adequate breathing.
Common medical conditions include:
- Pneumonia.
- Poisoning, especially from toxins affecting the respiratory control center in the brain, such as ether poisoning or the use of sedatives.
- Violent asphyxia, caused by physical force that halts breathing during one of its stages. This is often of concern to criminal investigators.
Conditions affecting the brain or nerves controlling breathing:
- Electric shock injuries.
- Poisoning.
- Paralysis caused by stroke or spinal cord injury.
Conditions affecting oxygen levels in the blood:
- Oxygen deficiency in the air, occurring in places filled with gas or smoke, or in elevator shafts and tunnels.
- Changes in atmospheric pressure at high altitudes, in unpressurized airplanes, or after deep-sea diving.
Conditions preventing the body from using oxygen:
- Carbon monoxide poisoning.
- Cyanide poisoning.
Signs of Asphyxia:
Asphyxia, regardless of its cause, shares a set of common signs:
External signs:
- Facial congestion, with blood spots in the eyes.
- Protrusion of the eyes and tongue sticking out of the mouth.
- Bluish discoloration of the lips, tongue, ear lobes, and fingernails.
- Presence of foamy bubbles around the mouth and nose.
- Visible cyanosis (blue discoloration) and blood pooling under the skin.
Internal signs: These are only visible during autopsy.
General symptoms and signs:
- Difficulty breathing: Increased rate and depth of breathing.
- The breathing may be noisy, accompanied by snoring or gurgling sounds.
- Foamy discharge from the mouth.
- Cyanosis (bluish color of the face, lips, and nails).
- Mental confusion.
- Decreased responsiveness.
- Loss of consciousness may occur.
- Potential cessation of breathing.
Violent Asphyxia:
Violent asphyxia refers to death caused by severe oxygen deprivation to the body's cells due to the disruption of the respiratory system by force. This can happen in the following ways:
- Obstruction of the external breathing openings (mouth and nose), called suffocation.
- External pressure on the neck, blocking the airways. This can be caused by manual strangulation or by using a rope, which is known as ligature strangulation.
- External pressure on the chest, preventing the muscles from breathing, as in cases of chest compression with a heavy weight.
- Obstruction of the airways by foreign objects or water, which occurs in drowning.
Suffocation:
Suffocation is a type of violent asphyxia in which the airways (mouth and nose) are blocked externally through pressure from hands, a pillow, a piece of cloth, or similar items to prevent air from entering the breathing openings.
In suffocation cases, in addition to the internal and external signs of asphyxia, the following localized marks are observed:
- Contusions around the mouth and nose due to the pressure applied by fingers, along with crescent-shaped nail imprints from finger pressure on facial tissues.
- Contusions and abrasions on the mucous membrane inside the mouth, caused by pressure from teeth.
- If a soft object like a pillow is used, there are no visible marks or abrasions.
- General signs of resistance, especially in adult victims.
Suffocation cases are often criminal, especially in children or the elderly due to their weaker resistance. It’s difficult for a person to suffocate another unless they are drugged, drunk, or the act is done unexpectedly and covertly.
Accidental suffocation may occur in infants if a mother falls asleep while breastfeeding and blocks the infant's nose and mouth with her breast. It is rare for suffocation to occur as a suicide because a person cannot keep their hands over their breathing openings; once the brain starts lacking oxygen, the person loses consciousness, and their hands relax.
Manual Strangulation:
Manual strangulation happens when pressure is applied to the neck with the hands, blocking the airways and the trachea. In addition to the common external and internal signs of asphyxia, the following signs may appear:
- Nail abrasions and contusions on both sides of the neck around the area of the larynx and upper trachea. Most manual strangulation cases are criminal and cannot occur as suicides. Accidental strangulation is also rare during play or wrestling.
Ligature Strangulation:
Ligature strangulation is a violent form of asphyxia where pressure is applied to the neck using a cord or similar material, causing death after a prolonged period. In addition to the usual external and internal signs of asphyxia, the rope may be found wrapped around the neck, often in multiple turns, with the ends tied securely.
In some cases, the perpetrator may untie the rope after committing the crime, leaving a circular, deep impression around the neck. This indentation typically reflects the shape and number of strands in the rope used. The depth of the indent is uniform throughout.
Most cases of ligature strangulation are criminal, and it is rare for them to be suicides. However, such strangulation can occur accidentally in children playing with ropes or imitating executions seen on television.
Hanging:
We often hear about court rulings stating, "Death by hanging." Execution by hanging involves suspending the body from the neck using a rope or similar material, either partially or fully.
There are four causes of death in hanging. Death from hanging by asphyxia only occurs if the rope is positioned in a certain way, with the knot at the back and the rope pressing against the front of the neck, using the body’s weight to force the tongue upward and backward, blocking the throat.
The other three causes of death in hanging are:
- Acute oxygen deprivation to the brain due to cessation of blood flow through the carotid arteries in the neck. The hanging weight stretches all soft tissues in the neck, including the carotid arteries, narrowing or completely blocking blood flow to the brain, causing cerebral anemia, unconsciousness, and immediate death.
- Pressure on the vagus nerve, leading to a sudden heart stoppage.
- Fracture of the second cervical vertebra, tearing the spinal cord that controls circulation and respiration, which happens only in judicial hangings during executions.
When you have a murder case, where the accused confesses and there are fifty witnesses who all agree that the defendant killed the victim at 12 PM, and the forensic doctor examines the body at exactly 4 PM, stating in the post-mortem report that the body was found in the fridge and was in the process of post-mortem decay (putrefaction)..
This statement will contradict the defendant’s confession as well as the witnesses' testimonies. How?
The phrase that the body was found in the fridge indicates that the body, since being placed in the fridge, will maintain its post-mortem changes, because the fridge’s role is to preserve the condition of the body as it was when it was placed in there.
The statement that the body was in the state of post-mortem decay means that the murder could not have happened less than 18 hours ago. This implies the murder happened yesterday or the day before (depending on the level of decay), which invalidates the defendant’s confession that the victim was killed at 12 PM, just four hours before the body was examined.
In cases where the defendant’s confession contradicts technical evidence (the forensic doctor’s report), the court will not consider the defendant’s confession because forensic evidence is stronger than witness testimonies and even the defendant's own confession.
In one case, the lawyer requested that the forensic doctor be summoned to discuss the issue of post-mortem changes. The judge replied, "Go back to any reference in forensic medicine and present it to the court."
Regardless of the court’s response, this issue leads us to refer to forensic medicine textbooks to understand the stages the body goes through after death. These stages can be summarized as follows:
Stage 1: Body Cooling: The body gradually cools until the internal temperature of the organs matches the surrounding air temperature. The body loses about 1°C per hour, on average, after three hours of death (meaning a noticeable difference between the skin and internal organs). To estimate the time of death, the body temperature is measured, then subtracted from 37°C and 3°C is added. For example, if the body temperature is 25°C, the time of death would be 37 - 25 + 3 = 15 hours. This means the death occurred 15 hours before the forensic doctor’s examination.
Stage 2: Livor Mortis: Blood settles in the lower parts of the body due to gravity, starting around 1-2 hours after death. It forms spots that gradually grow and become fixed after 6-8 hours. If livor mortis is fixed and does not change, it means death occurred more than 8 hours ago.
Stage 3: Rigor Mortis: This refers to the stiffening of the body and muscles, starting with small muscles and the jaw (making it difficult to close the eyelids or jaw). Full rigor mortis is complete within 8-12 hours, and after another 12 hours, it begins to gradually subside in the same order, with full relaxation occurring about 36 hours after death. In warmer weather, rigor mortis occurs and resolves in half the time due to higher temperatures. The stage can be further divided as follows:
- If the body is warm and relaxed, and the livor mortis spots are just beginning to form, the time of death is less than 3 hours.
- If the body is warm and stiff, and the livor mortis is not fixed, the time of death is around 3-8 hours.
- If the body is cold and stiff, and the livor mortis is fixed, the time of death is around 8-36 hours.
- If the body is cold and relaxed, and the livor mortis is fixed, the time of death is more than 36 hours.
Stage 4: Post-Mortem Decay (Putrefaction): This stage involves bloating of the body, the formation of bubbles under the skin, and the expulsion of foamy liquids from the mouth and nose. The body decomposes gradually, and soft tissues are consumed by maggots, eventually leaving only the bones connected by joints. The stages of decay are:
- Greenish discoloration appears on the lower part of the abdomen, typically after 18-24 hours in summer and 36 hours in winter.
- The veins on the skin’s surface become visible, around 36 hours in summer and 48 hours in winter.
- Greenish discoloration spreads across the entire abdomen and chest, with bubbles and the tongue protruding, after about two days in summer and three days in winter.
- Swelling of the face and abdomen, with flies laying eggs in the body’s natural openings, occurs after three days in summer and 5-6 days in winter.
- The face's features disappear after about 5 days in summer and 10 days in winter.
- The abdominal wall ruptures, and internal organs are exposed after 10 days in summer and 20 days in winter.
- All ligaments and cartilage decompose, leaving only bones connected by ligaments after 3 months in summer and 6 months in winter.
- Ligaments and cartilage decompose fully, and bones start to separate after 6 months in summer and about 12 months in winter.
Note: Decomposition occurs more slowly in water (e.g., in drowning cases) than in air. The “Kaspar’s Rule” states: "The signs of decomposition in a body exposed to air after one week are the same as those in a body submerged in water for two weeks or buried in the ground for eight weeks."
These are the key stages the body goes through. Since all this is medical information, I should mention the references:
- Crime Scene Investigation by Dr. Hisham Abdel Hamid (Head of Forensic Medicine Department).
- Principles of Forensic Medicine and Toxicology for Law Enforcement by Dr. Raga’a Mohamed Abdel Maboud.
- Forensic Medicine: Principles and Facts by Dr. Hussein Ali Shahrour.
This article is about determining the time of death. As for the location of death, it can often be identified by the bloodstains around the body or the livor mortis, which can help determine whether the victim was killed in the place they were found (according to witness statements) or whether they were killed elsewhere and moved after death. This topic will be covered in a separate article later.
