Monday, 11 March 2013

Timeline of occurences after death


First Hour

Immediately after death, all muscles in the body would relax. This is also known as primary flaccidity. In addition, the jaws may be hung open, the eyelids would relax, the joints and limbs would become flexible and the pupils would enlarge. Since the muscles are relaxed, the skin would be saggy. Joints and bones, like the hips, becomes noticeable. Since the heart has stopped beating, the circulation of blood will stop too, causing a person to become pale. This process is also known as pallor mortis. Next, algor mortis, the decrease of body temperature after death, takes place.

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Second- Sixth Hour
Now, livor mortis, a process whereby blood flows to the areas of the body nearer the ground due to gravity, occurs. Around the third hour of death, all the muscles in the body stiffen. This process is rigor mortis. It starts from the eyelids, neck and jaw to the toes and fingers. However, in deaths of younger children and infants, rigor mortis might not occur as they have fewer muscles in their body.
Seventh- Twelfth Hour 
Rigor mortis would be at its maximum 12 hours after death. However, this is dependent on the deceased's gender, age, physical condition, the temperature and so on. During this period of time, it would be hard for the limbs to be moved. The toes and fingers may be crooked while the elbows and knees would be slightly bent.
After Twelve Hours
After reaching the peak of rigor mortis, the muscles would relax as chemical changes within the cells takes place and there is tissue decay. However, this process is gradual, occurring over a few days. The external conditions include the factor on the speed of the process. All the muscles will relax again, from the toes and fingers to the jaws, eyelids and neck. This would be known as secondary flaccidity.


Sunday, 10 March 2013

Causes of Death


Scenario One (Arson Victims)
Arson

When a body is found at the scene of  fire, the corpse is firstly examined for soot in the breathing passage. The presence of soot would suggest that death was caused by asphyxiation, and the victim dies due to the lack of oxygen. In other cases, burns on the corpse with inflamed edges (caused by red blood cells trying to repair the burned skin), would mean that the victim  die from the burns. Wounds and injuries on the body may be a result of the fire, however, if there are signs of underlying bleeding , the victim was already dead before the fire began and the fire was just to cover up another crime.


Scenario Two (Victims Hanged)

A body which is discovered hanging will usually show signs of death due to the lack of oxygen. These include blue skin colour, burst blood vessels in the eyes and inflated lungs. The rope marks on the victim's neck will be compared to the rope found at the crime scene. The slightest difference of the rope impression from the actual rope itself would mean that the rope was not the murder tool.Forensic pathologists will then examine the rope marks on the neck to check if they contain evidently inflamed edges which is a sign that the victim was alive even before being hanged.  All rope markings on the neck should be in the shape of an upside down V, where the knot would cause a wound on the back of the neck, creating the point of the V.

 Strangulation usually breaks the hyoid bone located in the neck, but the bone  will barely be broken during hanging. The breakage of the hyoid would suggest manual strangulation. When strangulation is the case, death may be caused due to the lack of oxygen, but more likely, as a result of the deliberate compression of the neck, causing an inhabitation, the situation where the stimulation of the neck's vagus nerve causes the heart to stop. In cases where the hyoid bone is not broken, but bruising is evident around the nose and mouth, a death is caused by smothering, dying due to the lack of oxygen.

 

 

Scenario Three (Victims Drowned)

Dead bodies discovered in water are eamined if water is present in the airway of the victim and if the lungs had swollen up. If such indications are noticed, the victim did actually die due to drowning. If bleeding had occurred in the lungs, it suggests that there was a struggle during the drowning.
mariovittone.com
drowning


 

 
 
 

Marks of Violence
 
Internal/External Examinations
During an autopsy, there may be no external signs that the victim suffered from a brain haemorrhage. Brain scans are the only way to reveal the fatal clots that may have been caused by a blow to the head. Changes in the appearance of skin colour may also lead to solving the crime.

Bruising
bruise
Bruising on the skin occurs when blood vessels are broken by  forceful contact with the skin, usually by something blunt. The shape of the bruise will then be able to tell which direction the blow was received from and colour of the bruise can indicate how long ago the injury had occurred. As bruising heals, it turns red-purple, to brown, to green and lastly, to yellow.  Strangulation also leaves bruising. The hands, cords and ropes usually leave a distinct mark around the neck in the shape of pattern on strangling agent. If the strangling agent is a very soft material, it may leave little or even no marks, but the dissection of the neck area is able to show tissue bruising beneath the skin.Bruising is an inaccurate way to decide how the victim had met their fate, as interpreting bruising is different for every person, due to the fact that people bruise at different rates and bruising continues for a short while after death.


Cuts

The shape of a cut on the skin can show whether the weapon had one or two cutting edges, while angle and direction of cut can reveal whether a death was accidental or intentional. For example, committing suicide would leave a wrist cut cutting towards the knife-carrying hand. Also, the deepness of the wound can show how much force was used during the stabbing and can also determine whether the criminal had  intended to kill his victim.                                                         
Cut


Gunshots
 Size of wound can be a guide to the type of gun and bullets used and burn marks around wound is able to reveal whether the victim was shot at close range or from a distance away. A weapon fired close to the victim makes a single, big wound while a weapon fired from far away leaves many individual wounds.

Burns
Burns discovered on the body might be the cause of death, as the body may go into shock and die if untreated. Small burns on the body might have been a result of electrocution,, but a dose of electric current may cause severe blistering where the electric current had first met the skin. Electrocution occurring in water often leaves the body unmarked.

Assault
Assault leaves injuries such as ruptures, internal bleeding and broken bones. During an assault, the abdominal organs are the ones that are easily damaged as the body offers no protection for them. Ruptures in liver and spleen cause wounds in the bladder and stomach. The victim usually dies from internal bleeding into the abdominal cavity rather than the failure of the organs. Broken bones occur most commonly in the nose, jaw and ribs because these bones are more fragile than the bones in the legs and arms.


 

Determining cause of death


Death is usually caused by one of these three ways:
Coma (failure of brain)

Syncope (failure of heart)

Asphyxia (failure of lungs)


·        

Coma is usually cause by one of these four ways:

-Fracture of the skull which compresses the brain. In homicides, this is usually caused by a direct head injury by a blunt implement.

-Some poisons

-Some narcotic and hypnotic drugs

-Medical conditions such as cerebral haemorrhage and brain tumour.


Syncope


-Natural heart failure may be caused by several degenerative diseases and they can be aggravated by shock.

-Some poisons

-Direct injury to heart


 Asphyxia (lack of oxygen) is cause by:

-Breathing air that has insufficient oxygen content

-Obstruction of oxygen supply by air passages being blocked

-Pressure on chest or abdomen which prevents breathing

-Paralysis of respiratory system by electric shock or poison




Common specific causes of death include:

·         Bludgeoning with a blunt instrument. It is only likely to be fatal if is on the head. Death is usually from skull fracture pushing fragments of bone into the brain.
·         Burning - usually killed by too much smoke inhalation. Bodies exposed to intense heat are stiffened. As burning is sometimes used to cover up other crimes, the presence of burns on the body need not imply that this was the cause of death.
·         Drowning - kills by asphyxia, as the lungs fill with liquid. Post-mortem signs:
-Fine white foam at nostrils and mouth

-Wrinkling of skin if it had been in water for quite a while.

-Water in stomach

-Also look for signs of alcohol and drugs which may have caused accidental drowning.





Pain after death


It is believed that dead people will feel pain long after death, though this might be a conservatively late estimate, but it is scientifically solid.
Organic pain is the body's response to an attack, being a physiological response to harmful stimuli.
Psychological pain is more complex, it is when you think of pain or unpleasant memories, making you feel the pain.
The way one dies can determine the duration of pain one will feel after death. For example, falling 200 feet to one’s death can cause enough pain to last for 3 months while people who died of heart attacks feel little or no pain within one week after death.
Erik Kartman, a Boston Coroner deduced that this could be because the equipment that humans use to sense pain does not close down at once after death and might take some time.
Other than that, it was also believed that the soul will be aware of everything as it leaves the physical body.
Sources:
http://www.gather.com/viewArticle.action?articleId=281474978512144
http://wiki.answers.com/Q/Can_a_person_who_has_just_passed_away_see_or_hear_people_around_them

Biological Happenings Within Post-Death Period


Friday, 8 March 2013

Rigor Mortis ( Stiffening)

Rigor Mortis is the stiffening of the body caused by chemical changes in the muscle.

In the skeletal muscle fibers, there are two main parts.
1. thick fragments, made of the protein molecule called myosin
2. thin fragments, made of the protein molecule called actin

When an action occurs, a biochemical reaction is set off by a nerve impulse that causes myosin and actin to stick together. Together, they pull the thick and thin filaments towards each other. When thousands of these filaments are pulled at once, muscle contraction will happen. Once the two molecules are stuck together, they cannot separate unless adenosine triphosphate(ATP) attaches to myosin and forces it to release. The body uses oxygen to make ATP. After death, there is no more oxygen, hence ATP cannot be made. The thick and thin filaments cannot slide away from each other, thus, the muscle remains contracted, causing rigor mortis.

process of muscle contraction

Monday, 25 February 2013

Liver Mortis ( Blood pooling) & Pallor Mortis

  Livor mortis is the process whereby blood settles in the lower parts of the body. It is also known as postmortem lividity and is a sign of death. This process results in a purple-red discoloration. As the heart no longer pumps blood to the body, red blood cells, due to gravity, will sink through the blood plasma without clotting factors, also known as serum. The amount of reduced haemoglobin affects how dark the blood is. However, this process does not take place in the areas with contact with the objects or the ground as the capillaries are pressed against. During decomposition, blood would seep through the vessel wall as they become permeable. Thus, staining the tissues. This is why blood accumulates in a specific part of the body due to poor circulation(hypostasis).

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Livor Mortis

Livor mortis begins between twenty minutes and three hours after death. During this time, the skin of the body would be blotchy. The blood changes from a fluid to a solid or rigid state in the capillaries four to five hours after death. After five or six hours, the skin would turn white when touched even though the blotches have joined up. Between six and twelve hours, livor mortis is at its maximum. After ten or twelve hours, the skin would be blue whether it is pressed or not. The blood gathers at the interstitial tissues.
Blood pooling


The presence or absence of livor mortis can act as a way of determining the time of death. Although it would appear like bruises, experts would be able to tell if it was a discoloration. Also, the discoloration reacts with poison. For example, the skin turns cherry pink if carbon monoxide was added. If they find out that livor mortis is present, it suggests that beginning or continuing CPR would be ineffective. Also, this process helps to indicate if a body had been moved. For example, if a body was facing down when found while the blood is accumulating at the back, it would show that the body was facing up at first.

Pallor Mortis
Pallor mortis is an earlier stage of livor mortis and it occurs almost right after death. The corpse's skin would begin to turn pale as there is no blood circulating in the body anymore. Thus, the blood in the body would sink to the part of the body nearest the surface due to gravity.




Algor Mortis (Body Temperature)


The body temperature of a dead body will decline until it reaches the temperature of its surroundings which takes about 8 to 12 hours on the skin, but the centre of the body will take much longer, probably three times the time to cool.




Body after death temperature graph
To determine the rate of cooling, the rectal temperature of the body and its surroundings will be taken at the place where the person died and before it is removed to the mortuary. However it varies as the location of the body and the temperature of the room they died in affects the cooling rate.

The time of death could be deduced using the body temperature as a factor, but many other factors can influence this estimate.  By assuming the body temperature loss is one and a half degrees Fahrenheit per hour and the normal body temperature is 98.4, an estimate of the time of death could be deduced.