Forensic Pathology

Forensic pathology is the study of the effects of trauma, injury, and unnatural diseases on the human body. It focuses on accidental, suicidal, and homicidal deaths where tissue damage is the main finding. Cases of poisoning are also included in forensic pathology, although not all poisons cause tissue damage.

Forensic pathologists are experts who work in the field of forensic pathology. They are particularly interested in investigating accidental, suicidal, and homicidal deaths where tissue damage is present. They examine the human body to determine the cause and manner of death.

Cases of poisoning are highlighted separately in forensic pathology because not all poisons cause tissue damage. Although they fall under the field of forensic pathology, the specific nature of poisoning cases requires separate attention and analysis.

dying of a heart attack, a stroke, kidney failure or complications related to Covid-19.

Deaths due to violence and the consequences of the injuries that result in death, deaths resulting from external physical factors that impact on the body, deaths resulting from the effect of a chemical substance, and deaths when an anaesthetic was administered or the person had a surgical procedure shortly before death.

individuals dying in a vehicle accident or being struck by lightning

A post-mortem examination is performed by a forensic pathologist in cases of sudden death without pre-existing illness, unexplained deaths, or deaths suspected to be due to an act or neglect.

An example of omission to act is when a person with no medical aid reports at a private hospital with severe chest pain but is refused medical assistance, and subsequently dies of a heart attack upon leaving the hospital.

An example of an act is when a person dies as a result of medication injected intravenously instead of into the muscle, such as with Bentyl which is used to treat stomach cramps.

The main responsibilities of a forensic pathologist at the scene of death include pronouncing/confirming the death, determining the manner of death (natural, accidental, homicidal, suicidal, or undetermined), determining the time of death, and obtaining clues and information to clarify what occurred at the scene of death.

The post mortem changes studied by a forensic pathologist to determine the time of death include rigor mortis, hypostasis, cooling, decomposition, and insects which start a life cycle on the body.

The objective of investigating the scene of death by the forensic pathologist is to obtain clues and information that can help clarify what occurred at the scene of death.

broken objects, overturned furniture, broken branches and twigs, trampled ground

position of the weapon in relation to the body, whether it is loosely held or tightly grasped

the most likely weapon

Possible signs include the position of the body, the match between rigor mortis and hypostasis with the body's position, tears or missing buttons on clothing, blood stains or gunshot residue on clothing, incorrectly fastened buttons or unzipped pants, wounds inflicted through clothes or on bared skin, and the amount of blood at the scene.

The position of bullet holes in clothing should correspond with the location of bullet wounds. If they do not align, it may indicate that the death scene has been staged to make the death appear like a suicide.

The amount of blood should be interpreted with great care. It should later make sense when an autopsy is conducted. It may also indicate that the location where the body is found is a secondary dumping site and that there is a primary site where the murder actually occurred.

The forensic pathologist should look for self-defence wounds on the back of the forearms, arms, palms of the hands, and fingers. Paper bags should be placed over the hands to collect possible biological material under the nails. Signs of sexual assault, such as removed or awkwardly positioned underwear, should also be noted.

Rigor mortis, hypostasis, cooling of the body

Decomposition, insects that start a life cycle on the body

It helps establish a window period for death, excluding possible perpetrators and substantiating witness testimony

Rigor mortis (RM)

The formation of lactic acid in the muscles

2 - 4 hours after death

Cadaveric spasm, also known as death grip, is when the tense muscles at the time of death retain their tense state immediately after death and persist into the period of rigor mortis. It is related to post-mortem rigidity as it is a phenomenon that occurs during the early stages of rigor mortis.

The presence of cadaveric spasm indicates that the person died under intense physical and emotional strain. It can be observed in cases of suicide, homicides, drowning and mountain accidents, as well as car, airplane, and train accidents, and deaths on the battlefield in wartime.

In cases where cadaveric spasm occurs, manipulation of the muscles would be impossible. The grip of the muscles, particularly in the isolated muscles of the arm and hand, becomes extremely tight and difficult, if not impossible, to release.

Cadaveric spasm disappears when the full effect of decomposition sets in, typically after approximately 48 hours. This is because cadaveric spasm is an early stage phenomenon that occurs during the initial stages of rigor mortis, and as decomposition progresses, the muscles relax and the grip loosens.

Rigor mortis (RM) is the stiffening of the muscles after death. It develops approximately 4-12 hours after death, starting with the smaller muscle groups and progressing to the wrists and ankles, knees, elbows, and hips. The maximum peak of RM is reached within 12 hours and persists for approximately 12-36 hours. After this, RM gradually disappears in the same order it appeared, also known as secondary relaxation/flaccidity. The period of development and disappearance of RM is influenced by factors such as environmental temperature and individual characteristics.

The period of development and disappearance of rigor mortis can be influenced by factors such as environmental temperature, malnutrition, body weight, physical activity before death, diseases causing elevated body temperature, and certain causes of death such as brain hemorrhaging, epileptic seizure, and strychnine poisoning.

The criminalistic value of rigor mortis is that it can help estimate the time of death. Rigor mortis develops, persists, and disappears according to a predictable timetable known as Nysten's Law. By studying the posture of the body, the pathologist can also determine if there was movement of the body after rigor mortis had developed.

Rigor mortis and cadaveric spasm are both states of rigidity/stiffness after death, but cadaveric spasm is much more intense in rigidity than rigor mortis. Cadaveric spasm is a rare phenomenon and is also known as instantaneous rigor mortis, cataleptic rigidity, or the death grip.

Hypostasis, also known as livor mortis or hypostatic congestion, is the purplish-red discoloration of the most dependent parts of the body after the heart stops beating. It occurs when blood settles or pools in the blood vessels under the influence of gravity due to the heart no longer circulating the blood.

Hypostasis causes purplish-red discoloration in the body because the deoxygenated blood (blood without oxygen) in the blood vessels is not carrying oxygen anymore. This deoxygenated blood gives the purplish-red color to the areas where it accumulates or pools.

Contact pallor or contact blanching refers to the pale patches that occur on the body where pressure is exerted by the weight of the body against a surface. In areas where the blood vessels are compressed due to this pressure, blood cannot flow, resulting in paleness. These pale patches are often found next to the purplish-red areas where the blood accumulates or pools, indicating the development of hypostasis.

The pale patches on a person's body are called hypostasis and they are formed when blood pools in dependent areas due to the force of gravity.

The predictable period of development for hypostasis is: 1-2 hours after death the first signs are noticed, 4 hours after death it is well developed, 8-12 hours after death it reaches a maximum peak.

The blanching test is used to determine if hypostasis is fixed. If the thumb is pressed on the livid area and it becomes pale after the thumb is removed, the hypostasis is not fixed. If the area remains purplish-red, the hypostasis is fixed.

The criminalistic value of hypostasis is that it can be used to estimate the time of death, determine movement of the body when hypostasis development does not correspond with the position the body is discovered in, and the color of hypostasis can be indicative of the cause of death.

The three distinct periods of algor mortis are: 1. The initial phase or temperature plateau when the temperature remains relatively stable for 30 minutes to three hours. 2. The intermediate phase in which the body cools rapidly and at a relatively linear rate. 3. The terminal phase when the rate of body cooling slows as the core temperature reaches the environmental temperature.

Some factors that can influence the rate at which a body cools down are: the difference between body temperature and environmental temperature, ventilation and humidity of the surrounding area, clothing, and body weight.

No, the post mortem interval cannot be accurately estimated during the first three to five hours after death due to the effect of the actual body temperature at death and the length of the temperature plateau following death.

Mummification and adipocere

Mummification

Adipocere

Moist conditions, acidic burial ground, presence of enough moisture, absence of oxygen

The two processes involved in decomposition are autolysis and putrefaction. Autolysis is the initial stage of decomposition, where cells leak enzymes and bacteria consume internal organs. Putrefaction is the visible stage of decomposition, which is separated into the bloating, decay, post decay, and dry stages.

The first noticeable sign of putrefaction is a greenish discoloration that appears on the lower abdomen near the right hipbone. This is where most of the bacteria in the intestines are present.

The bloating of the stomach during putrefaction is caused by gas formation inside the body, mainly hydrogen sulphide, ammonia, carbon monoxide, and methane.

The phases of decomposition after death are bloating (approximately 5-6 days), decay (approximately 11 days), post-decay (starts around the 12th day after death), and dry stage (approximately 3-4 weeks).

Post mortem purging is the drainage of fluids from the body and it occurs during the decay phase, which lasts for approximately 11 days.

Some factors that can affect the rate of decomposition include sepsis before death, environmental temperature, humidity, presence of insects and other animals, and burial or exposure to open air.

Terrestrial animals like rats, dogs, and cats eat soft exposed tissue and tend to choose areas where the skin is already broken, enlarging wounds sustained ante mortem. Aquatic animals like leeches, turtles, crabs, and fish also eat tissue and can produce injuries that resemble different types of wounds.

blowfly

around the eyelids, nose, mouth, ears, genitals, anus and open wounds

up to 300

The different instar stages of maggots are instar 2 and instar 3. It takes 2.5 days for maggots to grow to 10mm long in instar 2, and 4 to 5 days for maggots to grow to 14-16mm long in instar 3.

After instar 3, the maggots become too heavy to hold on to the body and fall to the ground. At this stage, they have grown to 17mm long and have reached maturity.

The pupal phase of a blowfly is when the maggots develop a hard brown shell around them. In favorable conditions, the pupal phase lasts within 6 to 8 days.

Studying the insects that start a life cycle on a body can assist in determining the post mortem interval and the minimum time the person has been dead.

An autopsy is performed when a death is considered possibly unnatural or upon request by a criminal investigator or instruction by a magistrate.

The criminal investigator in charge of the investigation is allowed to attend an autopsy.

No, permission from family members is not required to perform an autopsy.

Post mortem abrasions are yellow, translucent, and have a parchment-like appearance (hard and stiff).

It is not possible to determine whether superficial abrasions were produced shortly before death or at some time thereafter.

The subtypes of abrasions are scratches caused by a sharp object passing across the skin, and abrasions caused by fingernails associated with throttling and strangulation.

Tear lacerations are caused when a body part touches a protruding object during the mechanism of overstretching. For example, if a body is ejected from a vehicle in an accident and a body part is thrown against a door handle.

Grinding compression lacerations occur when the weight of a rotating object against the skin tears the skin off from the underlying tissues, producing a pocket of fat and blood on the site of compression. For example, when a tire of a moving vehicle passes over the abdomen of a person lying in the road.

Incised wounds, or cuts, are caused by sharp-edged instruments, such as knives, blades, or shattered glass, being drawn against the skin. These wounds usually have smooth, clean-cut edges and their length is usually greater than their depth.

Chop wounds are produced by heavy sharp-edged instruments like axes, hatches, and pangas. They result in a cut in the skin by the edge of the weapon, and the weight and force of the weapon also produce contusions at the margins of the wound.

The different types of abrasions are: strangulation with a ligature produces a linear mark around the neck horizontally, hanging produces groove abrasions in a V-shape rising towards the point of suspension, scrape or brush abrasions are caused by rough objects coming into contact with the wider surface of the skin, impact, impression or pressure abrasions occur when blunt force trauma is applied to the skin, friction abrasions are caused by linear pressure on the skin accompanied by movement.

Contusions, also known as bruises, are blunt force injuries that cause veins and capillaries under the skin to rupture, resulting in blood escaping into the tissue beneath the skin. Factors that influence the appearance of contusions include the location and tissue characteristics, age, sex, texture and color of the skin, and certain diseases.

Lacerations occur when the skin and tissue below the skin tears as a result of excessive stretching. They can be produced through splitting of the skin when it is crushed between two hard objects or through overstretching of the skin when it is stretched beyond the capability of the tissues to withstand the force being applied.

The shape and appearance of contusions are influenced by factors such as the location and tissue characteristics, age, sex, texture and color of the skin, and certain diseases.