In crime scene investigation, before any items of evidence are moved, photographs must be taken from different angles to show respective positions of various items of evidence, including the victim. Photographs should also be taken after various objects are moved, for cartridge cases or bullets may be found under the victim’s body, or they may be hidden by pieces of furniture, etc.
Bullet holes in the walls, floor, and ceiling or in the furniture should be photographed. Before undressing, the body should be photographed. After the clothes are removed, entrance and exit holes should be photographed with identifying labels and rulers.
The bullets, pellets, and wadding found in the body should be photographed. All areas likely to bear suspect’s fingerprints, such as door knobs, glassware and the weapon should be examined for fingerprints.
EVIDENCE FROM SCENE in crime scene investigation
- The gun.
- Fired bullets.
- Empty cartridge cases, shells and wads.
- Hairs, fibers and bloodstains.
- Objects struck by or containing spent bullets, e.g. wood, cement, etc.
- Glass shattered in firing.
- Areas showing fingerprints and footprints.
EVIDENCE FROM SUSPECT in crime scene investigation
- Clothes with trace evidence.
- Victim’s hair, clothing, fibers and blood.
- Gunpowder and other evidence on the hands.
- Gun used in the crime.
- Unspent ammunition and empty cartridges or shells.
AUTOPSY in crime scene investigation
Clothing may be forced into the tissues in shotgun wounds. Probes, fingers, etc. should not be introduced through the defects in the clothing, as the direction or distribution of fibers will be changed and cause confusion in deciding the entrance and exit of it.
Number the entrance and exit wounds
In the case of multiple wounds, it is advisable to give a number to each injury, disregarding whether it was caused by entry or exit of it. This is essential in crime scene investigation. The clothes should be preserved carefully in clean brown paper or plastic bags and sent to Forensic Science Laboratory for testing. The powder grains adherent to clothing should be carefully removed with forceps and preserved in a glass vial, as they may be lost from the clothes due to rough handling.
Clothes should be folded in such a way, that the area of holes and gunpowder soiling are not disturbed or contaminated. Infrared photography can be used to find out soot deposit on dark colored or black fabrics. Ordinary X-ray can be used to search for larger metallic fragments for elemental content.
Bullet Wounds in crime scene investigation
If there are multiple injuries, they should be numbered. On the body diagrams, the injuries should be drawn as they appear on the body including burning, blackening, tattooing, abrasion collar, etc. Photographs of the injuries should be taken in crime scene investigation. Bullet wounds must be described with care.
- the exact location of each wound should be noted in relation to its distance from the top of the head or the sole of the foot,
- mid line of the body,
- a fixed anatomical landmark, e.g., “in the chest, 50 cm. below the top of the head, 8 cm. to the left of the mid-line and 2 cm. above the nipple”. The size and the exact appearance of it is not preserved after excision due to the cutting of the elastic fibers.
External Wound in crime scene investigation
(a) The character of the perforation, its shape (stellate, round, slit-like or irregular), and size should be noted. The hole in the skin should be carefully measured first, and then the abrasion collar and the powder pattern surrounding the borders of the entrance. Difference in the width of the abrasion collar at different points should be noted as they indicate the angle at which the bullet struck the skin. A circular one requires only one diameter of measurements, e.g., the skin perforation is round and measured 8 mm. in width. It is surrounded by a uniform rim abrasion 2 mm. in width. An elliptical one is measured across its widest and narrowest diameters and variations in width of abrasion recorded, e.g., the skin perforation measured 8 mm. by 3 mm. with the larger diameter running horizontally. A rim abrasion measuring from 0.5 mm. to 2 mm. surrounds the skin perforation with the wider area located at its lateral side.
(b) The presence or absence of blackening and tattooing should be specifically noted, e.g., blackening and tattooing are absent, or the skin perforation is surrounded by an area of blackening and tattooing measuring 8 cm. by 5 cm. with the larger diameter running vertically.
(c) Skin splits, contiguous and non-contiguous.
(d) Muzzle imprint.
(e) Soot deposit, including the corona.
(f) Metal deposition.
Alteration by medical care personnel
A scaled photograph or a diagram showing the numbered wounds is useful in crime scene investigation. It is advisable to record the wound in the skin and track through the body in one section. If the entrance is soiled with blood, it should be sponged carefully so that any tattooing of the skin may not be disturbed.
After it has been examined, the skin around the entrance and exit injuries should be cut out including at least 2.5 cm. of the skin around and 5 mm beneath it. They should be packed separately in rectified spirit, labelled and sent to the Forensic Science Laboratory.
If surgical wounds are made on a shotgun or stabbing victim, the surgeon should make adequate documentation of their location and nature in his records or on the hospital chart, so as to prevent confusion, if the patient dies and an autopsy is performed.
Track taken by the Bullet through the Body
Bullet tracks should be numbered and described individually in crime scene investigation. Probes should not be introduced through the track. The path taken by it through the body should be carefully traced by dissection with the organs in situ.
It is useful to measure the height of both entrance and exit wounds from the under surface of the heel. This shows the direction of the track, and also the height above the ground at which it entered and left the body, if the person was in standing position when struck. The track should be described in relation to the planes of the body:
- from front to back or from back to front,
- from left to right or from right to left,
- from above downwards (caudad), or from below upwards (cephalad).
Angular estimates, i.e., vertical, horizontal and sagittal planes of the body are also useful to complete the description. To release it from the bone without actually handling it, the segment of bone containing it should be excised, or sawed, followed by manual bending. Frequently, the track of it is unpredictable due to its deflection by bone, and it may be found in a most unexpected situation of crime scene investigation.
When a cavity has been penetrated and blood has collected, it should be searched in the effused blood. A high velocity bullet is rarely deflected. To avoid prolonged search for it in the body, X-ray examination should be done before autopsy.
Rib borders or the border of other bones must be examined for roughening or fracture, which may explain the deflection of bullet, If there are multiple tracks, each should be followed from the point of entrance to termination. The track made by it widens as it goes deeper.
If it grazes a bone, it may produce a gutter with or without fracturing it. If it passes through the bone, a track of tiny radio-opaque metallic particles removed from the surface of the bullet will be seen in X-ray.
The size of pellets is difficult to measure after the shot is tired as it becomes deformed. All bullets and recognizable parts of it in the victim must be recovered, and described as to where it was found, whether it is intact, deformed or fragmented, whether it is lead or jacketed, etc.
Next to bone, the skin offers the greatest resistance to the penetration of it. A bullet passing through the body may come to rest just underneath the skin on the opposite side. The type of missile and the point of recovery should be noted. The location and character of exit wounds should be noted. All wadding in the body should be recovered to know gauge of the shotgun and the type of ammunition.
When a rapidly traveling object is slowed by passing from a thin to a dense medium, there is a release of kinetic energy which may be so violent as to fracture bones in the immediate vicinity of the track although the bones are not actually struck.
Shock waves will also pass through the tissues causing injury remote from the actual wound. When a high velocity missile passes through soft tissue, it is followed by cavitation due to the released energy.
This primary cavity then collapses, and is followed by lesser secondary cavitation, which creates a negative pressure and debris is sucked into the track. When a high velocity missile strikes a relatively solid internal organ, such as the heart, this organ may disintegrate as if an explosive charge has been detonated in its substance.
Part of the energy of it is spent by the tip to break the resistance of the tissues, and another part to push the tissues aside. This radial displacement producing transient cavitation is important with regard to the severity of tissue damage.
If almost all the energy of it is lost during penetration of the scalp, bone and dura, it passes through the brain without producing cavitation until it comes to rest. If the bullet passes through the brain with great velocity, the wound track expands immediately after it has passed through.
This expansion develops in few microseconds, during which time brain is suddenly pressed against the inner table of the skull and other firm structures, and momentarily bulges out of entrance and exit wounds and collapses equally fast.
The track of damage may be 4 to 5 times the diameter of the bullet, as seen by a track of hemorrhagic pulped brain tissue. Prior to cavitation of brain, skull fractures result. If the fractures extend beyond the area of entrance and exit and the cavitation is very severe, the skull may burst by the pressure of the brain.
A large portion of the brain may be thrown out of the bursting skull and found relatively intact. This is known as KRONLEIN SHOT. If such explosion does not occur but cavitation is severe, the sudden pressure on the tissues surrounding the wound track causes immediate necrosis due to shearing forces acting on submicroscopic structures of cells. A ring of tissue hemorrhage is found outside the necrotic tissue.
Contusions are also produced at a distance from the wound track due to displacement of portions of the brain due to the sudden space-occupying entrance into the brain and by the associated cavitation.
They occur independently of the location. Small caliber, low velocity bullets produce cavitation but fail to perforate the head on the opposite side. Sometimes, the entire track or one segment of it is found several times larger than it. This occurs when it passes sideways through the tissues or when it tumbles.
Bullets may be found in or on bodies either due to being fired from a gun or having been discharged from the cartridge as a result of heat-induced explosion. An exploded bullet does not show land.and-groove markings and the cartridge case is devoid of firing-pin impression. Intense fire causes melting of ammunition and leaves a pool of molten lead which may stick to the body as tiny droplets. X.ray shows ‘bird-shot’ pattern in films.
DESCRIPTION OF A FIREARM WOUND in crime scene investigation
There is a gunshot wound of entrance in the left anterior thoracic wall. This is just above and immediately medial to the left nipple and is situated 40 cm. below the top of the head and 10 cm. to the left of the midline. It is circular in shape, 0.8 cm. in diameter, and is made up of a 0.2 cm. radial dimensional abrasion ring concentrically placed about a 0.4 cm. diameter defect. There is no soot deposit or powder tattooing.
A small amount of blood comes out from the defect upon manipulation of the body. A track is established from the gunshot wound of entrance on the left anterior thoracic wall, passes through the third interspace, through the lingua of the left lung, through seventh thoracic vertebra. Here, embedded in the bone, is recovered a full metal jacketed bullet of 0.25 caliber. This is marked ‘X’ and retained. A left haemothorax of 1200 ml. of tluid and clotted blood is present.
PRESERVATION, MARKING AND PACKING OF EXHIBITS in crime scene investigation
All bullets recovered from the body must be preserved with correct labeling of the relationship of each bullet to the corresponding wound. This is important in case of dacoity or rioting, to know which of the several weapons may have fired the fatal shot. It is important to state from which portion of the body, or from which internal organ it was removed.
When more than one bullet or other foreign object has been removed from the body of a victim, or found in or about his clothing, each one should be labelled and placed in separate envelope.
Care must be taken in removing it from the body so that marks due to artefact, such as, scratches are not produced on it. Such markings may make difficult subsequent identification of it. It is preferable to remove the bullets with bare fingers.
A forceps protected with rubber tubing may be used. The appearance of it should be described accurately, e.g., intact, deformed, fragmented, lead or jacketed and the caliber if known. The bullet should be weighed, and if its base is not deformed, the diameter of the base should be measured.
The recovered one should be dried and not washed, because washing removes the powder residue. In shotgun injury, the pathologist need not recover every pellet present. A few pellets should be recovered for the ballistic expert to determine the shot size and possibly type of ammunition.
(1) Firearms: Identifying initials should be scratched on to gun’s frame, receiver, or slide and on the gun barrel.
(2) Fired Cartridge Cases : The identification mark should be scratched on the inside of the open end. They may be wrapped in cotton and packed in cardboard boxes.
(3) Fired Bullets: The identification marks should be scratched on the base, or just above the rulings on the ogive but not on the end of the nose, for the nose may pick up trace evidence, e.g., the pattern of the weave of fabric through which it has passed. It is wrapped in cotton and packed in cardboard box. Each bullet should be packed separately in crime scene investigation.
(4) Pellets, Slugs, Wads, etc: They may be packed in cardboard box with cotton after drying and the container labelled.
(5) Clothes : The area of the powder tattooing should be preserved by fastening a cellophane paper over it, and packed in a box.