Asphyxiation

Death by strangulation is due to asphyxia, which is the inability to breath due to obstruction of the respiratory system. Strangulation is a common form of murder, as it is considered clean and easy. Fortunately there are many signs of asphyxia. As asphyxia takes place there is a decrease of oxygen and increase of carbon dioxide to the blood and tissues, causing the skin to take on a purplish colour (known as cyanosis). Blood-staining may appear around the mouth and nose, and Petechiae (spots of haemorrhage) appear due to the bursting of small capillary blood vessels. When a person is being strangled they often vomit, however it must be taken into account that the vomiting may have caused the asphyxia instead of being a result of asphyxia. There are forms of asphyxia, such as choking on food, which could happen naturally, so the investigator would need to be sure whether the death was accidental of murder. Tell-tale signs of murder are strangulation marks on the neck or maybe fibres in the throat and lungs from smothering.

A very common form of asphyxia is drowning. When someone drowns the air passage and stomach are filled with water, causing death. If a body is found drowned but has been moved away from the water they drowned in, the original scene of death can be located by examining the water found in the body. Any debris in the water may be traceable, and natural bodies of water often contain diatoms (microscopic algae - see right image), which can often be pinpointed to particular bodies of water.

If a person is found drowned in the likes of a lake or river, it is often questionable whether the death was accidental or murder. People found drowned wearing swimming costumes often drowned by accident, though this is not always the case. People committing suicide often remove certain items of clothing beforehand. If a person is found drowned in very shallow water it is almost certain that foul play is the case, though disabled or sick people may not always be able to save themselves in shallow water.

All of these aspects must be looked at when trying to determine whether a death due to asphyxiation was accidental or on purpose.

Blunt Instruments

Among one of the most common methods of murder is using a blunt instrument as the murder weapon. Murders commited this way are usually unpremeditated, often crimes of passion or the result of a heated argument turned violent. The use of a blunt instrument, though it may not seem too dangerous, can be fatal, especially since most attacks this way are made to the head. The outcome of striking someone with a blunt instrument depends on two things; the weight of the object, and the force behind it. The resulting force of the blow can be expressed as the following equation: E=(m x v2) divided by 2. (E=kinetic energy, m=mass, v=velocity).

The use of blunt instruments in murder is seen as being unprofessional yet very unpleasant. A scene of crime where a victim has been killed by force of a blunt instrument to the head is often messy, as several well-aimed blows to the head is often enough to crack open the head, splashing blood about the scene. Once the skull has been cracked open, damage to the brain will occur (even if the skull is intact damage to the brain membranes can still occur). Such a force to the brain can lead to haemorrhaging, skull fracture, or most likely death.

The below image shows a CT scan of a person's brain suffering from an Intacerebral haemorrhage.

The blunt instruments used to murders can be anything, as the use of them to commit a killing is often spontaneous. Instruments used tend to be any object around at the time.

Gunshots

Probably the most common form of murder is shooting. Firearm shootings are most common in the United States, however cases of shootings are increasing rapidly in all countries.

It is said that the exit wound of a bullet is much larger and more ragged that the entry wound, the case is not always so. It all depends of the nature of both the bullet and the part of the body the bullet enters and exits. The entry wound is larger than the exit wound if the bullet is moving through flesh, however this is not that common an occurrence as the bullet usually hits bone. When the bullet does hit bone, it either ricochets off the bone and stays in the body, or it exits. If it exits, the exit wound will be larger than the entry wound. If a bullet does hit bone it often ricochets in a different direction. The angle of the bullets path can often be determined.

The entry wound can often be distinguished quite easily. If when fired the gun was held quite close to the skin, there will be soot and residues around the wound. If the muzzle of the gun was held to the skin when shooting, the skin around the wound will be black and maybe pinkish in colour due to the emission of carbon monoxide. The entry hole will be star-shaped or splintered if fired at close-range. The further away a shot is fired, the neater the entry wound will be, and there will be less blackening of the skin.

There are four types of gunshot wound. Contact wound - The muzzle of the gun was applied to the skin at the time of shooting, Close Range - The muzzle of the gun was 6-8 inches away from the skin at shooting, Intermediate Range - The gun was 8 inches to 3.5 feet away, and Distant - The gun was over 3.5 feet away at the time of shooting.

In the case of a fatal shooting it is often debated whether it was murder or suicide. Obviously if the distance at which the bullet was fired is greater than arms length, it could not possibly be a suicide. Discoloration of the skin suggests suicide, though there still may be foul play involved. The location of the entry wound is also important. Suicides very rarely shoot themselves in the torso, so that would assume foul play. Gunshots to the head could be either murder or suicide.

Stab Wounds

Stabbing is, and always has been, a very common means of murder. One single stab wound could cause very little harm at all, yet depending on just where it enters the body, it could very well be fatal. Stab wounds are associated with the likes of knives, however blunter objects such as closed scissors or a poker can also be used to inflict this wound. We can usually tell what sort of instrument the victim has been stabbed with by looking at the wound itself. If the wound is small a neat, maybe no more than a slit, then it is clear that something very sharp such as a knife was used. When the wound is larger and ragged, it was inflicted by a blunter object. We can usually measure the length of the instrument used by measuring the depth of the wound itself.

But how do we know when an inflicted stab wound is homicidal or suicidal? Suicides by stabbing is becoming less frequent these days, what with the simpler choices of drugs and firearms available, but it does still occur. Cutting of the wrists and throat are often associated with suicide, whereas stab wounds to the back are obviously unlikely to be suicide. When committing suicide the person rarely kills them self with one clean stab or cut to the wrist or throat - there are mostly several hesitation cuts before the final, fatal cut is made.

We can also determine whether a cut or stab wound was made by another person by looking at the position of it. If a person has been stabbed in the back, it is very unlikely, if not impossible, that they inflicted the wound them self. When examining cuts we can look at the direction the cut moves to help understand who the wound was inflicted by. There are some directions a cut could move in that would be impossible for the victim to inflict themselves, which points to murder.

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