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CENTRAL BUREAU OF INVESTIGATION
ACADEMY
FUNDAMENTALS
OF
FORENSIC SCIENCE
(VOL. - III)
A Hand Book for Investigating Officers
KAMLA NEHRU NAGAR, HAPUR ROAD
GHAZIABAD
INDEX
FORENSIC SCIENCE (VOL.III)
S.No. Topic Page No. 1 TELEGRAPH .a Introduction .b What is Telegraph? .c Collection of Evidence .d Methods of Analysis .e Traction Wires and Cables .f IIllustrative Cases 2 TYRE IMPRESSIONS & SKID MARKS .a Introduction .b Tread Characteristics .c Direction of Travel .d Recording Tyre Impressions e Skid Marks
3 SOIL, DIRT AND DUST
.a Soil - Introduction .b (^) Nature of Soil .c Collection of Soil .d (^) Dust & Dirt .e Collection of Dirt and Dust .f (^) Illustrative Cases. 4 RESTORATION OF OBLITERATED MARKS .a Introduction .b Type of Marks .c Principle of Restoration .d Techniques of Restoration .e Etching Reagents Used. .f Restoration of Wood .g Restoration of Plastics .h Restoration of Leather I Illustrative Cases. 5 RESTORATION OF OBLITERATED MARKS .a Introduction .b Nature of Marks .c Location of Tool Marks .d Collection of Evidence Bearing Tool Marks .e Principle of comparison of Tool Marks .f Preparation of Test Marks .g Comparison of Marks .h Illustrative Cases.
6 MECHANICAL FIT
.a Introduction,
.b Examples of Mechanical Fit.
C Illustrative Cases
7 FINGER PRINT EXAMINATION
.a Introduction.
.b Importance
.c Method of Taking Finger Prints.
.d Types of Finger Print Impressions,
.e Classification of Finger Prints.
f. Single Digit Classification.-
8 FOOT PRINT EXAMINATION
.a Introduction,
.b Protection of scene of crime,
c. Preparation of Foot print casts.
9 EXAMINATION OF COUNTERFEIT COINS
AND COUNTERFEIT CURRENCY
.a Introduction,
c. Applications of Infrared Rays.
15 X-RAYS
.a Introduction,
.b Source of X-rays.
.c Application of Soft X-rays.
d. Application of Hard X-rays.
16 PHOTOGRAPHIC SUPERIMPOSITION
.a Introduction
.b Nature of Photograph required for superimposition.
.c Nature of Skull required.
.d Superimposition Technique.
e. Electron Skull Superimposition Technique.
17 THE POLYGRAPH (LIE DETECTOR)
.a Introduction.
.b Development of Polygraph.
.c The Principle : What is Psychosomatic interaction?
.d The Instrument
.e Procedure.
.f Environmental Conditions for Polygraph Test.
.g Precautions.
.h The Questioning Techniques.
.i Test Questions.
.j Control Questions.
.k Peak of Tension Questions.
.l Analysis of Polygraph Chart.
m.The legal status of the Polygraph Test.
18 VOICE IDENTIFICATION SPECTROGRAPH
.a Introduction.
.b Development of Sound Spectrograph.
.c Reliability, Principle & Technique.
.d Bar Voice Print and Contour Voice Print.
.e What attempts to disguise voice?
f. Legal status.
19 DNA FINGERPRINTING (PROFILING)
.a What is DNA?
.b Nucleotides.
.c Source of DNA.
.d DNA Profiling Technique.
.e Procedure for DNA profiling.
.f Polymerase Chain Reaction Technique.
.g Prospects of DNA fingerprinting in India,
.h h) Autonomous DNA profiling Centre.
.i Forensic Application of DNA Test.
j. Illustrative Cases
20 BALLISTICS - FIREARMS, CARTRIDGES,
BULLETS, RANGE OF FIRE & EXPLOSIVES
.a Introduction.
.b Important Questions
.c What it studies?
.d Characteristics of Firearms.
.e What is Rifling?
.f Difference between Pistol and Revolver.
.g What is Caliber, Gauges, Ammunition?
h. What is Bullet and Gun Powder?
21 INVESTIGATION OF CASES INVOLVING FIREARMS
.a Introduction .b Gunshot Residue Analysis. .c Collecting Firearms Evidence. .d When a dead person is holding the gun. .e Position of Bullet. .f Handling of Firearms. .g Cartridge Cases. .h Bullets, .i Small Shot .j Test Firing. k. Powder pattern examination. (^22) ARSON EVIDENCE .a Introduction, .b Arson Investigation. c .Physical Evidence. (^23) EXPLOSIVES .a Introduction .b What is Explosive? .c Low Explosives, .d High Explosives. .e Blasting Agents. .f Military Explosives. .g Homemade Explosives, .h Blasting Caps, Matchheads, Smokeless powder i. Ammonium Nitrate Fertilizer & Potassium or Sodium Chlorate (^24) BOMB SCENE INVESTIGATION .a Introduction .b Search. c. Role of Crime Laboratory
1. TELEGRAPH. Introduction Pure copper wire, being highly conductive, was used as means of communication line by the telegraph department for quite sometime. These wires were laid over the length and breadth of the country. Likewise railway tracks running electric trains are provided with traction wires made of pure copper. Telephone and electric cables are laid on the poles or underground.
The cost of copper has increased enormously over the years. Owing to the high price and great demand for copper, criminals have found it a profitable business to steal telegraph and traction wires. Nowadays, due to paucity of copper, aluminum wires are used in the place of stolen copper wires. Even these are reported stolen, as they too have a good market value. The Government attaches great importance to these cases, because apart from the loss of public property, they seriously disrupt a vital communication system of the country. To check on the growing menace of this property crime, the Government has enacted a law as discussed below:
What is Telegraphic Wire? "Telegraphic Sire (Unlawful possession) Act of 1950 has been formulated which regulates the possession of telegraph wire and provides punishment for the offence of unlawful possession of telegraph wires.
The Act has been amended further to make it more severe. Section 2(b) of the Telegraph Wire (Unlawful possession) Amendment Act, 1975 defines telegraph wire as any copper wire the diameter of which in millimeter is :
(1) not less than 2.43 and not more than 2.53 (150 = 3 lbs/mile) or, (2) not less than 2.77 and not more than 2.87 (200=4 lbs/mile) or, (3) not less than 3.42 and not more than 3.52 (300=6 lbs/mile) Section 5 of the same Act states "whoever is found or proved to have been in possession of any quantity of telegraph wire which the Court has reason
to believe to be,......., the property of the Posts & Telegraph Department..........shall, unless he proves that the telegraph wires came into his possession lawfully, be punishable with imprisonment for a term which may extend to five years, or with fine, or with both".
Collection of Evidence This moment theft is reported by the Telegraph Department the Investigative Officer is required to visit the scene of offence and collect the cut ends of the wires remaining on the poles. These form the control samples of the cut ends. The end cut by the Investigating Officer should be bent to distinguish it from that cut by the culprit. The control end is then protected by covering with cotton. The Telegraph Department staff is also authorized to collect the cut ends, resting on the poles, in the same manner and hand them over to the police at the time of reporting of theft. The Investigating Officer should then make a search for the stolen wire and the cutting tool. The seized property along with the cut ends should be sent to the laboratory for matching the cut ends with the seized tool. To determine whether the copper wire is the property of the Telegraph Department, the services of the Divisional Engineer Telegraph Department could also be sought, besides forensic laboratory.
Methods of Analysis The seized copper wire can be examined in the laboratory using one or more of the following methods :
- Measurement of gauge of wires - Measuring the gauge of wire is very simple. With the help of micrometer screw gauge the diameter of the wire is measured at different places to get an average gauge. If the diameter falls within the specification of the Act then the seized property can be confirmed as the property of the Telegraph Department.
- Matching of cut ends for tool marks - Before using the questioned tool for test cuts, the blades should be tested for the presence of
The traction wires and cables, which may be the property of the Railways, Telephone or Electricity Department, are also vulnerable for thefts. They, however, do not fall under any legislation for unauthorized possession as in the case of telegraph wire. This makes it difficult for the department authorities to identify the stolen property, on recovery as their own. In such cases reliance has to be placed on its trace element profile by spectrographic or Neutron Activation Analysis. If the tool used for cutting the wire is seized then the cut ends can be matched with the test cut ends. Similarly, the stolen cables can be examined for the number of wire strands, their thickness, number of cores, nature of core material etc.
ILLUSTRATIVE CASES
Case 1. In a case of theft-cum-murder two ceiling fans were reported stolen. The fan wires are snapped from the connecting electric wires which were collected by the Investigating Officer. The stolen fans were subsequently recovered along with the snapped electric wires. They were sent to the laboratory for examination. On examination, they were found to have transparent tape below the outer rubber sleeve. The tape under the outer rubber sleeve revealed the markings of the manufacturer. This along with the matching fit of the snapped wires, gave ample proof of their common source. The cas ended in conviction.
Case 2. In one case of theft of the Telegraph wires, the Telegraph Department lodged a complaint of theft of telegraph wires. They also produced 15 cut ends from the poles where the wires were cut. The police team immediately requisitioned the services of the Dog Squad. They were lead to a distant village hut where huge dump of stolen copper wire was located. The suspect was apprehended along with his accomplices. Two pliers were recovered from their possession. Few ends from the wires were cut and sent to the laboratory, along with the two pliers and 15 cut ends, produced by the Telegraph Department. On examination it was possible to establish link of both the pliers with the ends collected by the Police. Whereas, the 15 cut ends, showed match with one of the two pliers. On the basis of the laboratory findings the case of theft was charge sheeted and the accused from whom the pliers were seized were convicted.
2. TYRE IMPRESSIONS AND SKID MARKS
INTRODUCTION The Motor Vehicles are increasingly being used in criminal cases. We have come across several terrorist cases where the terrorists used to move from one place to another to commit violence, dacoity and theft. In several murder and rape cases, either dead bodies are carried in the vehicle to dispose off them at distant place or to abduct a woman for sexual assault. Thus the use of vehicle in committing crime is on the increase.
The modern criminal finds the automobile as an indispensable part of his equipment, in the commission of crime, disposal of dead bodies and for other criminal activities. Tyre impressions left at the scene of a crime may at times form the only clue to the perpetrator.
In unusual circumstances, a characteristic feature of a tyre such as an inserted patch, or a peculiar injury to the tyre may be noted. In such cases identification may often be made with a very high degree of certainty. Usually, no such feature will be present and only the general nature of the tread will have to be examined.
Tread Characteristics.
The characteristics of tyre treads are altered by the manufacturers. Over a period of time considerable modifications may take place. Most tyres have a parallel series of zig-zag ridges. The widths between them may often be different; the ratio of length of a section to its width may vary ; the degree of parallelism of the ridges may be quite different. In some tyres the ridges are wholly or partially cut transversally, in order to grip a smooth roadway more effectively, while others are designed to create a vacuum on the road when compressed. The tyre tread should be studied with regard to the following features :
Skid Marks
When the brakes of a speeding car are applied suddenly, the friction between the tyre and road heats the rubber, depositing a thin layer of rubber particles. This is noticeable as black mark is the path of the tyre. This mark is called skid-mark.
In a motor vehicle accident the Investigator has often to determine whether the cause of accident is due to deficiencies in the brakes or due to rash and negligent driving. Usually the only evidence present is a set of skid marks. These marks may be shown to be a measure of the probable stopping distance, i.e., the distance travelled by the vehicle from the moment of full application of brakes to the moment the vehicle comes to a stop.
The length of the skid marks depends upon the speed of the vehicle, its total weight, the condition of its tyres and the nature of the road surface. For the calculation of the speed, a test skid mark is created at a reasonable known speed on same or similar road and with the same vehicle if available. Having measured the length of the skid mark produced at the scene, and the length of the test skid mark at known speed, the speed of the vehicle at the time of meeting with an accident can be determined by the following formula :
V1 = V2 (S1/S2) 2 /
Where V1, S1 refer to the speed and skid length relating to the accident and V2, S2 refer to the speed and skid length of the test driven vehicle respectively.
3. SOIL , DIRT AND DUST SOIL Introduction Soil evidence may be encountered in a wide variety of criminal investigation. It may be found on the shoes, clothing or the underside of the motor vehicles. It is useful in lying the suspect or victim to a location. A tire or footwear impression in soil makes it possible to prove that the subject was in fact present.
Soil is present at every crime scene in one form or the other and is usually collected as a heterogeneous mixture which may include clay, sand, rock, coal, plant material and other debris. It is usually associated with outdoor crime scenes, but may also feature in indoor scenes.
In many cases soil is either deposited at or carried away from a crime scene. It may be found on the suspect, his shoes, his clothing, his vehicle or tools used in the crime. It may be found at the scene of hit-and-run accident where the soil present on the under carriage of the vehicle may have fallen due to impact. The evidence of soil is often overlooked because investigators are unaware of its potential value or of the laboratory services available to exploit it.
Nature of Soil The term “Soil” may include any disintegrated surface material, both natural and artificial, that lies on or near the earth’s surface. It is formed from rocks and minerals by the weathering process and later it gets pulverized with plant, animal and manufactured products. Soil, therefore, encompasses not only the naturally occurring rocks, minerals, vegetation and animal matter but also includes manufactured materials like glass, paint, chips, asphalt etc., which may impart soil with characteristics that will make it unique to a particular location. Further variations in soil are caused by man due to mining, agricultural and industrial operations where there is almost constant mixing and moving of soil.
- For trace material like glass, dust, soil etc. , envelops should not be used.
- The packing of the evidence should be so thorough that further breakage of the physical evidence should not take place in transit.
It should be kept in mind that when an exhibit containing trace evidence is found at the scene of crime, several specimen samples from immediate vicinity should be collected to enable the laboratory to compare the physical evidence. Such representative specimen would ensure whether the physical evidence collected belonged to the scene of crime or otherwise.
Samples of mud and grease from the frame and the mudguards of the automobiles form an important physical evidence in the hit and run cases. The physical evidence found at the scene of occurrence or on the body of the deceased could be compared with those on the suspected vehicle in order to link the vehicle to the crime.
In cases of burglary, dacoity and theft, several materials like traces of plaster, dust, fibres, glass etc., also may be found as physical evidence in such cases. If the materials on the clothing of the suspects are microscopic, they can be collected by means of a special vacuum cleaner containing pouches for collection of such minute evidence.
Physical evidence collected from the scenes of crime, especially sand and soils can be compared with the representative samples collected from the scene of crime by means of density gradient analysis technique, where various particles like sand, organic material like humus get separated depending on their density. This is the simplest and accurate method in the analysis of soil and sand. In addition to this method, the trace evidence also can be examined by means of a spectrograph to find out the elemental composition in various samples of sand and soil, glass, paint flakes, metal pieces etc.
DUST AND DIRT
Dust is usually characterized as being composed of microscopic particles which cannot be categorized under any specific evidence. Such dust may be very characteristic of a particular place. This applies especially to places such as flour mills, building sites, workshops, coal mines, saw mills and the like. A person who has worked at or visited such a place carries on his clothes dust characteristic of that place and may reveal his occupation or his visit to that place. The evidentiary value of this nature can be of paramount importance, and often a clinching factor.
Dirt on the other hand is a material which is transmitted or acquired usually by accidental contact, the ingredients of which may have come from a varied source. A typical example of dirt will be the residue from a suspect shoe, which when examined by immersion in water, in a dish, may reveal leaf, vegetable matter, fibres, seeds etc. After separation and drying qualitative analysis may ascertain the nature of the mineral ingredients. The analysis of vegetable ingredients present in the dirt may point to be places visited by the suspect.
Collection of Dirt and Dust Dirt and dust specimens removed from garments by several methods. Large quantities are removed by the usual mechanical means of scraping and picking off with tweezers or shaking out. Garments may then be placed in clean paper bags and beaten to remove dust or may be collected directly into a filter paper by means of a special vacuum cleaner device.
Dirt in the fingernails is scrapped and collected in a clean paper. Scrappings from different fingernails should be packed separately.
Dust and dirt from pockets and trouser folds should be collected by means of a small clean brush.
Case 3. In a case of hit and run accident a cyclist was knocked down who subsequently succumbed to the injuries. At the site of the accident a cake of mud was found, which appeared to have fallen from the under surface of the vehicle’s mud-guard as a result of sudden stoppage. The suspect car was traced. The sample of similar cake of mud was collected from the under surface of mud- guard close to the portion which was found missing. Comparison of the two mud cake samples revealed close similarities which helped to corroborate the involvement of the vehicle in accident and conviction of the driver.
4. RESTORATION OF OBLITERATED MARKS
Introduction Manufacturers of valuable items, like automobiles, bicycles, firearms, watches, sewing machines, art objects etc., often register serial numbers on their products as a means of identification or to establish ownership. Individuals in possession of expensive silver or stainless steel wares frequently get their names inscribed on these articles for identification. When criminals steal such property they may attempt to alter or erase the identification marks by either filing the surface bearing marks with file or by using sand paper or grinding wheel. It is almost impossible to alter such marks without leaving obvious evidence of an attempted erasure. Forensic laboratory can restore such erased numbers or names enabling the police to identify the stolen property with the owner. Restoration of obliterated marks is often possible in the laboratory, partly or wholly.
Type of Marks Three types of marks are commonly found on the articles : (i) Cast Marks - These type of marks are raised above the surface of the metal, but sometimes cast marks may sink into the metal surface. Such marks form part of the mould and appear on the metal surface when it is cast. Cast marked numbers or names do not generally identify the main product. It may only identify a component of the product. If the cast marks are erased, it is not possible to restore them and is not of much help either.
(ii) Engraved Marks - Two types of engraved marks are common, marks engraved by using chisel, and those made with an electric engraver. If marks made by chisel and electric engraver are obliterated, it can be restored provided the erasure is not too deep. But the success of restoring engraved numbers is much less than in the case of punched numbers or marks. This is
