Strangulation

Strangulation implies pressure to the neck, and deaths due to strangulation are therefore of immense forensic importance.

It can be defined as a circumferential squeezing of the neck that is independent of the gravitational weight or suspension of the head.

Categories of Strangulation

	manual strangulation
	ligature strangulation
	choke holds

Signs

	obstruction of jugular veins with impaired venous return to the heart, leading to cyanosis, congestion, petechiae etc
	obstruction of carotid arteries (which can cause cerebral ischaemia)
	stimulation of baro-receptors in the carotid sinuses and carotid sheaths
	elevation of larynx and tongue, closing the oro-pharynx

Manual Strangulation

Otherwise known in the UK as 'throttling' and in the USA as 'choking', this mode of death is usually caused by men against women, and rarely against another man due to the requirement for there to be a large disparity in physical strength between the assailant and victim.

Signs of manual strangulation ...

	disc-like finger-tip bruises (although it is unwise to over-interpret such bruises, as hands may be changed over during the course of the attack, making it difficult to distinguish between single handed or double handed attacks, and between left or right handed assaults etc)
	abrasions
	linear finger-nail scratches (from the assailant, or the victim when trying to remove the assailants hands from the neck)
	often limited signs of suffocation as fingers are more likely to probe deeper neck structures and cause reflex cardiac arrest
	sustained pressure may cause congestion and blueness of the tongue, pharynx and larynx
	haemorrhage under the skin of the neck and bruising of the strap muscles (where suffocation is suspected, the neck is dissected after the great vessels of the thorax have been emptied, to enable the dissection to be carried out in a relatively bloodless field, so that post-mortem artefacts are not mis-interpreted)
	damage to the larynx - particularly the superior horns of the thyroid cartilage, and the greater horns of the hyoid bone

Manual strangulation (Ed Lulo's Site)

Ligature Strangulation

Where a constricting band is tightened around the neck, there is usually gross congestion, cyanosis and petechiae in the face if the pressure is maintained for more than about 20 seconds.

The ligature mark is a vital part of the evidence, as it often reproduces the pattern and dimensions of the ligature itself. If the assailant has removed the ligature from the scene, and is subsequently arrested, possible ligatures found on the assailant or in his home etc can be compared with the mark on the victim's neck. Some modern techniques involving computer imaging are being developed to assist in this comparison process, in much the same way as pioneers in the field superimposed photographs of suspected victims over skulls of unidentified persons.

Ligatures that have been left on the neck after death, or which have caused sliding friction over the skin result in a brown-coloured dry leathery band, and there may be a red 'flare' of vital tissue reaction on either side of the ligature. The mark is usually horizontal, just above the laryngeal prominence ('Adam's apple'). It usually continues around the circumference of the neck, sometimes with a cross-over or knot. There will not be a rising peak indicating a suspension point, unlike in cases of hanging or suspension.

Ligature marks represent the nature of the ligature, ie. soft, fabric based ligatures may leave a diffuse mark, whilst wires or cords leave a deeper more defined mark.

External skin markings may include scratches from the struggling victim, and the internal injuries may include those seen in manual strangulation, but are often less obvious or developed.

Suicidal strangulation by ligature is less common, but there may be a ligature wound around the neck several times, involving complicated knots.

Choke Holds

These include the so-called 'carotid sleeper' and 'bar arm' choke holds that are sometimes used in law-enforcement situations, although they are increasingly being outlawed in many jurisdictions.

There is often little or no external neck injury visible, whilst haemorrhages in the strap muscles can be more extensive and broader in nature. If the bar arm hold has been of sufficient strength, the airway may have been obstructed, leading to 'air-hunger', and and lead to violent struggling on the part of the restrained person.

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