17/04/2012
CONTINUATION CRIMINAL INVESTIGATION:
Each transfer of evidence should be receipted. The recipient of evidence shall be accountable during the time it is in his possession, record the name of the person from whom received and to whom it is delivered.
f) Protection of the Physical Evidence: The evidence must be presented in court in the same substantial condition as it is at the time the offense was committed. It must be protected from:
i. Natural Alteration- Exposure to outside elements may result to the deterioration of the evidentiary value of an object. Rain, high temperature, may affect the evidentiary value of an object. Blood samples may loss its blood grouping property by refrigeration.
ii. Negligence and Accidental Cause- Precaution against breakage, destruction of fragile or delicate materials, accidental markings on documents and others must be prevented.
iii. Intentional Cause, Damage or Theft- Measures should be made and provided to maintain security of evidence.
g) Labeling/Tagging of Physical Evidence- This is to facilitate proper identification of the pieces of evidence being collected. This may take in the form of paper pasted on the container or a tag tied to the object. The following information should appear in the label or tag:
i. Case number;
ii. Date & Time--- of finding the article
iii. Name & complete description of articles;
iv. Location of the article(s)--- at the time of discovery;
v. Signature of the investigator---who made the discovery;
vi. Name of witness(es)--- during the discovery of article.
I. SEARCH OF THE CRIME SCENE:
Not all crimes produce a “crime scene” in the sense that traces of its commission are usually found. Crimes like FORGERY and EMBEZ ELEEMENT do not usually produce a distinct crime scene wherein the Investigator can focus his attention.
When a crime scene has developed on account of the commission of a crime, the Investigator must have a thorough search of it to find traces of its commission.
Traces may be left in the form of clothing, shoe impression, finger-prints, blood stains, over-thrown furniture, disturbed articles, and others. (traces in the crime scene may be viewed in an “active” as well as “passive” sense, namely):
1. The effect of the criminal on the scene.
2. The manner in which the scene may have imparted traces of the criminal.
Preliminary Steps to be observed by the Investigator on Arrival at the Scene of the Crime:
a. Identity and, if possible, retain for questioning the person who first notified the Police.
b. Determine the perpetrator by direct inquiry or observation if its identity is immediately apparent.
c. Detain all persons present at the scene.
d. Summon assistance if necessary.
e. Safe-guard the area by issuing appropriate orders and by – physically isolating it.
f. Subsequently permit only authorized persons to enter the area.
g. Separate the witnesses so as to obtain independent statements.
h. Do not touch or move any object.
i. Definitely assign the duties of the search – if assistants are present.
Assignments of Duties:
Only one-Investigator may be assigned to handle a case when it is a minor one and the work-load of the office is great. When a cast is relatively important, and to insure thoroughness of the investigation, several investigators may be assigned – to handle the case.
If there are many Investigator assigned to form a team, to insure maximum effectiveness, the following arrangement is recommended:
a. Officer-in-Charge: One who direct search, assign duties, and assumes responsibility for effectives of the search.
b. Assistant: He must implement the order of the Officer-in-Charge.
c. Photographer: Photo the scene and individual pieces of evidence.
d. Sketcher: Makes a rough sketch of the scene and later – a finished sketch.
e. Master-Note-Taker: One who writes down in short-hand the observation and description given during the search.
f. Evidence Man: Collects, preserves and tags articles of evidence.
g. Measurer: Makes over-all measurements of the scene.
The Search:
Before the actual search is done, the Investigator must stand aside and make an estimate of the situation. A certain area where there are no possible traces of the crime, may be made as the – “headquarters”.
Having formed the estimate, the investigator can now determine the number, kind and views of the photographs he wishes to be taken.
A plan for the search should be formed which will cover all the ground. Every step of an investigation must be undertaken with the though of ultimate presentation in court.
The basic guide for the Investigator to look upon are evidences to establish one-or more of the followings:
1. The Corpus Delicti or the facts that the crime was committed.
2. The Method of Operation of the perpetrator.
3. The identity of the guilty party.
Mechanics of the Search:
If the area to be searched is limited, indoor with few contents or any other situation which will preclude a systematic search, no standard procedure of search is recommended. Any method of choice will do provided that alertness, knowledge and experience of the participating Investigation are present.
If the area to be searched is quite extensive, a more systematic scheme of approach is recommended. The following are the different methods of search.
1. Strip Method: The Searchers (A, B and C) proceed slowly at the same pace along the path parallel to one-side of the rectangle. At the end of the rectangle, the searcher turn and proceed back along new lanes – but parallel to the first movement.
(In the modification of the Strip Method, known as “double strip or grid method”, the rectangle is traversed first parallel to the base, and then parallel to the side).
2. Spiral Method: The Searchers follow-each-other in the path of a spiral, beginning on the outside and spiraling-in towards the center, - or vice versa.
3. Zone Method: The area to be searched is divided into – quadrants, and each searcher is assigned in each quadrant.
4. Wheel Method: If the area to be searched is approximately circular or oval, the wheel method may be used. The searchers gather at the center, and proceed out-ward along radii or spokes. (The principal draw-back of this method is that, - the distance between searches increases – as they depart from the center).
The Investigator must see to it that the search made with the employment of any of the above-methods must be thorough.
The discovery of any physical evidence in the course of the search must be collected and preserved without specific regard to their relation to the crime. (Basically, a searcher must preliminary concentrate on the following types of evidences):
1. THOSE, which establish the element of proof, that the crime was committed;
2. THOSE, which may serve to-trace the criminal.
Reconstruction of the Crime:
After completion of the search, an effort must be made to determine form the appearance of the place and its objects what actually occurred and, what are the circumstance of a crime is known as – “reconstructing the crime”.
Kinds of Reconstruction:
1. Physical Reconstruction: The physical appearance of the crime scene is reconstruction from the description of witnesses and the indication of the physical evidence.
2. Mental Reconstruction: After physical reconstruction some conclusion can be made concerning the consistency of the accounts of various witnesses. No assumption should be made – concerning actions which are not supported by evidences. (The final theory developed by the Investigator should provide a line-of-investigative-action).
Equipments in the Search:
1. Searching Tools: (Flash-light, Magnifier).
2. Sketching Instruments:
a. Measuring Devices: (Compass, Steel Tape, Ruler).
b. Recording Implement: (Chalk, Graph Paper, Sketching Pad, Clip Board, Paper Pad or note – taking).
c. Collection of Evidences: (Cutting-Filers, Knife, Screw Driver, Shear/large scissors, Scalpel, Dropper, Forceps, finger-print equipments.
d. Preservation of Evidence:
Container: Bottles, Envelope, Test Tubes, Pins, and Thumb Tacks.
Label and Seal: Evidence Tags, Gummed labels, Sealing Wax, and Grease Pencil.
II. PHOTOGRAPHING THE CRIME SCENE:
The following are the minimal-requirements to be observed by the Investigator – to insure admissibility of photographs in – Court.
1. The object which is represented – should not be immaterial and irrelevant.
2. The photograph – should not unduly incite prejudice or sympathy.
3. The photograph – should be free from distortion/deformity.
Distortion in Photographs May Assume any of the Following Forms:
1. Incorrect Point of View: The photograph may obscure essential objects and emphasize other.
2. Perspective: Distortion of the picture may be due to the improper-relationship of focal length of lenses of print viewing distance and tilting of the plate or lens board.
3. Tone: Mis-representation of tone can be accomplished by manipulation of exposure, development and choice of printing paper.
Photographing the Crime Scene:
There must be a series of Photographs of the crime scene – to supply the maximum information, and to enable the viewer to understand how the crime was committed.
Kinds of Photographs at the Crime Scene:
1. Over-all Photographs: Carried in clockwise, until at least, four-general view photographs have been taken.
2. Photographs of the Deceased: A set of views showing the relationship of the dead body – with the surroundings.
3. Photographs of Articles of Evidence: Weapons, Blood Stains, Hair, Fibers, Papers, and others, seen at the crime-scene must be photographed before removal.
4. Special Techniques: (This will include the used of motion – picture apparatus, projection work and other techniques).
5. Photographs of the environs/surroundings.
6. Photographs of the body (after removal).
(For identification of the victim);
(Close-up pictures of the wounds).
Photographic Data:
A complete record of each photograph should be made in a notebook – so that the following minimum-essentials are available:
1. Data to identify the photographs with the offense;
2. Data to identify the photographer;
3. Data to orient the camera-position with the scene;
4. The data and hour when each photographs is taken;
5. Data reflecting the light and weather condition when each photograph was taken;
6. Data reflecting the type and make of camera, film and details regarding special equipment used;
7. Focal length of the lens;
8. Data regarding developing, printing and any special laboratory technique;
9. Data to reflect – a complete “chain pf custody” of the photographic film used.
III. CRIME SCENE SKETCH:
The “sketch” is the simplest and the effective way to showing actual measurements, - and of identifying significant items of evidence in their location at the crime scene. (Sketching is supplementary to Photography).
Kinds of Sketch:
1. Rough Sketch: Made by the Investigator at the crime scene. No scale, proportion ignored, and everything is approximate. (It will be used as a basis of the finished sketch).
2. Finished Sketch: Made preliminary for court-room presentation. (Scale and Proportion observed).
Sketching for the Police may be:
1. Sketch of Locality: The sketch of locality gives a picture of the scene of the crime and its environs, including such items as neighborhood buildings, roads leading to the location or house, and others. (IN ARSON CASES, the sketch of location is of great-value as an aid in determining whether the fire was caused by nearby-inflammable property).
2. Sketch of Grounds: The sketch of grounds pictures the scene of the crime with its nearest physical surroundings, like a – house with garden, The plan of one-or-more floors in a house and so forth.
THE CRIMINALISTICS LABORATORY
A criminalistics laboratory utilizes the skills of professional criminalist, technical assistants, questioned document and latent fingerprint examiners, photographers, and polygraph examiners. Criminalists are university gradutes holding degrees in criminalistics and related physical sciences. Other staff members may hold various degrees in connection with the duties they perform. All staff members must eventually be qualified to present expert testimony before courts in connection with the services they render. Some laboratories may also include a surveyor and a composite artist as staff members. Many laboratories are organized in section, each responsible for specific functions. Note: A major portion of the information and illustrations in this chapter are form the Physical Evidence Manual, State of California, Department of Justice, Division of Law Enforcement, Investigative Service Branch, with permission from the agency.
THE FI****MS SECTION
This section conducts fi****ms identification examinations, comparison of firearm and bullets, studies to determine trigger pull, operation of safety devices, alteration or modification of weapons or any condition of the weapon that might cause accidental fire or make it unsafe.
Functions
The fi****ms Section is responsible for:
Test firing of all fi****ms.
Comparison of bullets and cartridge to evidence guns.
Securing all fi****ms.
Restoration of serial numbers.
Clothing analysis for gunshot evidence.
Analysis of any fi****ms-related evidence.
Fi****ms Identification
Each firearm has an individual set of characteristics which can serve to identify it, even though it is compared with one of the same type, model, caliber and manufacturer. Individual characteristics will be found as follows:
1. Barrels: No two barrels are microscopically identical. Rifling (which consists of a number of spiral grooves) is cut into the surface of the bore to provide the fired projectile with rotation, stability and direction in motion. This rifling is individual with each barrel, and leaves raised portions (“lands”) which are actually original surfaces of the bore before the rifling is cut. Both grooves and lands will contain identifiable characteristics due to the individual cutting (boring) process and the character of the steel tubing the barrel was made from. The rifling may have a right-handed or left-handed twist. Either twist may be constant throughout the bore or increase from the breach to the muzzle. The number to grooves may vary from four to six. The grooves and lands of the bore may be of equal width, or broad grooves and narrow lands, depending on the manufacturer. Other characteristics of rifling are the pitch, the measure of the rate at which the direction of the groove changes; diameter bore, the distance from land to land; and groove diameter, the distance from bottom to bottom of opposite grooves.
2. Caliber: This is the diameter of the bore measured in hundredths of an inch. Example: A .30 caliber gun is one in which the bore has a diameter of 30 one hundredths of an inch.
3. Firing Pins: These are individually finished during manufacture and contain file marks and pit marks which will leave an impression on the primer of the bullet when it is fired.
4. Extractor Marks: These marks are produced when the extractor under spring tension is forced over the rim of the case in loading the cartridge into the chamber. This occurs in the use of automatic, self-loading, bolt, pump and lever action rifle and shotguns and automatic pistols.
5. Ejector Marks: These are produced on the base of a casting or the rim or fl**ge, when the fired cartridge is drawn from the chamber by the extractor. They are normally found on cartridges fired from self-loading and automatic weapons.
6. Breech Face Marks: These are produced on the primer of the cartridge when the gas pressure generated at the time of firing forces the cartridge against the breech face, or in the case of rifles, the bolt head. Again, the principle of individual characteristics applies to extractor and ejector marks, as well as breech face marks. File marks as a result of manufacturing are present, often augmented by marks acquired through the use in firing.
7. Ballistics: All test concerning ballistics and bullet would also be a function of the Fi****ms Identification Section of the crime laboratory.
8. Experts: It is not uncommon to find that the fi****ms expert is also the explosives expert charged with the highly hazardous duty of handling and disposing of explosives van and specialized equipment for this service.
9. Trace Metal Detection Technique: It is possible to demonstrate that a person has recently held a gun in his hand. Research has determined that metal objects leave traces on skin and clothing surfaces in characteristics patterns with intensities proportional to the interaction of weight, friction, or duration of contact with metal objects. The trace metal detection technique makes such metal trace patterns visible when skin or clothing is treated with test solution (hydroxyquinoline) and then is illuminated by ultraviolet light. A spray container is generally the most suitable method of applying the test solution. Test areas are allowed to dry thoroughly prior to examination. The parts of a test area that have been in contact with metal object give off fluorescent colors that are unique to each metal:
Iron, steel = blackish-purple
Copper, brass = purple
Galvanized iron (tin) = bright yellow
Aluminum = mottled dull yellow
Lead = buff (flesh tone)
The pattern of the metal traces, as revealed by the fluorescent colors is traced. Handguns leave distinctive patterns which are specific to types, makes, models and caliber of these weapons. The shape, size and weight of the gun or metal object, the duration of contact and the use of the metal object all combine to produce the location and intensity of metal trace and their patterns on the hands. It has been found that metal trace patterns have developed up to 36 to 48 hours after contact when the suspect has followed a normal routine of daily hand washings. Fluorescence photography reveals the preserved metal tracings.
Restoration of Obliterated Serial Numbers
It is, on occasion, possible to restore serial numbers that were originally on metal (i.e., engine blocks, guns, etc). When the number was originally stamped into the metal, the molecules of the immediate area became compressed, “crushed,” and otherwise distorted and the metal molecules were thrown out of line to varying degrees. This compression actually leaves a shadow below the original numbers, approximately half the original depth of the pressed number. When the serial number is ground off, this shadow remains below the surface, unnoticed, undisturbed.
Etching
This method is applied if the serial number has been ground off. The area where the original number was located is cleaned and then highly polished with an abrasive (emery cloth). The area is then surrounded can be nitric, hydrochloric or sulfuric acid in a reagent, and is applied with a swab. With care and patience the original number may appear if the acid does not eat away the shadow position. It is obvious that the experienced laboratory technician with the knowledge of the various reagents and their affects on various metals is required for this testing. If the number is restored, it must be promptly photographed for recording purposes.
Magnaflux
This method is also used if the serial number has been ground off, though reports of success with it are not as frequent as with acid etching. In this technique the metal surface is prepared in the same manner as with the acid etching. The metal is then magnetized, wherein the crystalline structure (shadow) below the visible surface draws the iron oxide in the applied flux (solution) and forms the numbers which are then photographed for recording purposes. It is important to note that these methods of restoration are useless if the serial numbers have been ground off too deeply or below the shadow area. On occasion, serial numbers are burned off with a torch or punched out which also makes restoration impossible. Examples of successful restoration are offered.
Fi****ms Tests
Dermal Nitrate test
Many research studies have clearly confirmed that the dermal nitrate paraffin cast techniques is worthless for determining whether or not an individual has fired weapon. In this technique the suspect’s shooting hand is coated with melted paraffin, and a reagent (diphenylamine) is dropped on the paraffin mold. The appearance of dark blue specks ostensibly indicates a positive reaction, i.e., presence of nitrates from gunpowder residue on the suspect’s hand. The great problem is that bleach, fertilizers, to***co, urine and other oxidizing compounds will cause the same reaction, thus proving only that an oxidizing substance-not necessarily nitrates- is present on the suspect’s hand.
Powder or Shot Pattern Test
An approximation as to the distance from which a gun was fired when inflicting a wound can be obtained by powder or shot pattern tests conducted in a laboratory. These test are based primarily on the spread of gunpowder residues on the skin or clothing of the victim. A contact or near contact wound will often cause a scorching of the flesh or cloth around the entrance, in addition to depositing gunpowder residue. Weapons fired at a distance greater than twenty-four inches will not normally deposit gun powder residue at a point of contact(entrance of bullet). The same weapon and same type of ammunition used in the crime is fired into white artist’s sketching paper from various distances until the approximate powder residue and shot pattern desired is achieved.
Neutron Activation Analysis
Only a few major laboratories are equipped to conduct these studies. Neutron Activation Analysis involves the irradiation of any unknown material with neutrons (nuclear particles). Some of the irradiated atoms in the unknown material become radioactive and disintengrate, giving off gamma rays. The energy of the ray is measured with a Gamma Ray Spectrometer. The energy values are used to identify the element(s) in the original material. Quantitative measurement of the elements in the evidentiary material with the radioactivity of known amounts of these elements. Extensive studies have been conducted of paraffin casts made on hands of individuals who have fired various weapons; however, to date this analysis cannot always establish whether or not an individual has fired a gun.
Atomic Absorption Method
Atomic Absorption is now replacing neutron activation analysis and the dermal nitrate paraffin test for determining whether or not a subject has recently fired a handgun. Neutron activation analysis is quite expensive, and the paraffin test is not always effective.
Atomic absorption analysis for detecting gunpowder residue on a suspect’s hands is relatively inexpensive. It not only detects antimony and barium (as doe’s neutron activation analysis) but also lead. Collection of gunshot residue is accomplished by spraying the hands of the suspected shooter with a five percent solution of nitric acid. The hands are then swabbed with a dry cotton-tipped applicator. Any gunshot residues (particles) that adhere to the swab are then analyzed. The analysis involves burning the test swab and comparing the frequency of the light given off by the sample with a known standard.
THE TRACE ANALYSIS SECTION
Trace analysis involves the examination, identification and evaluation of numerous types of physical evidence collected in criminal investigations. The studies conducted by the section would include the microscopic examination of slides taken from r**e victims during the pelvic examination conducted by a physician. The microscopic examination and comparison of fibers, hair, tool marks, pry marks and wood chips are other examples of the studies conducted in this section. The shoe and tire prints and imprints obtained at crime scenes by investigator or criminalists, as well as soil samples, debris, paint, glass and plastics fragments collected during the investigation are also analyzed by this section.
THE SEROLOGY SECTION
The Serology Section conducts all ABO typing of blood, semen and other body fluids. The following describes several basic tests for these.
Tests for Presence of Blood
Presumptive Test (Benzidine TMB Reagent): This is a presumptive test: it does not establish the presence of blood. It is used as a screening test to determine if a stain may be blood. If the test is negative, this would eliminate the stain as not being blood.
Method: Moisten a piece of clean filter paper with distilled water and touch the edge of the stain. Apply a drop of the reagent to the absorbed stain on the filter paper. If a blue coloration appears, this indicates a positive reaction.
Confirmatory Test (Hemin): This test is used to establish the presence of hemoglobin in a suspected blood stain.
Method: A small portion of the suspected blood stain is placed on a slide and intermittently treated with a drop of saline solution and glacial acetic acid. When dry, the substance is examined under a microscope. If blood is present, brown rhombic hemin chloride crystals have formed.
Biological Perciptin (Ring Perciptin): This test is used to establish the origin of blood stain as to species, human or animal; and if animal, what kind: dog, cat, hog, chicken etc.
Method: This test is conducted in a test tube, and a positive reaction can be observed as a ring of precipitate which transform at the interface of an extract of a blood stain and the antiserum. Note: To identify a stain as human blood, an antihuman serum is used. This antiserum factor applies to the testing of animal blood as well.
Blood Grouping: Blood grouping test will establish which of the four major blood groups a stain belongs in (i.e., O,A,B, or AB). Blood grouping involves the agglutination, or clumping of erythrocytes (red blood cells). Note: The author will not attempt to treat the methods of analysis involved in blood grouping, as they are beyond the intent of this text.
Tests for Presence of Semen
Preliminary Test (Florence): This test is used to determine the presence of choline. Seminal plasma is one of the richest sources of choline. A strong positive reaction indicates the stain may contain semen, though this is not a specific test as a positive reaction may also be produced by tissue extracts. In addition, false negative reactions may be caused by blood grouping, as they are beyond the intent of this text.
Method: The test is conducted by adding a drop of Florence Reagent to an extract of a suspected seminal stain. If dark brown choline-periodide crystals form, they can be viewed under a microscope.
Confirmatory Test (Microscopic Examination): The conclusive identification of stain as semen depends on the presence of male reproductive cells (spermatozoa) in the stain. This is determined by microscopic examination of the stain.
Other Body Fluids: Many human beings secrete the blood group substance(s) corresponding to their major blood group in their body fluids (e.g., semen, saliva, vaginal secretions, etc). These persons are known as “secretors”. Those persons whose body fluids do not contain the major blood group substance(s) are called “nonsecretors.” It is, therefore, possible to establish the presence of the ABO blood group from stains of semen, saliva, vaginal fluid, etc., derived from secretors. Approximately sixty percent of the population are secretors.
THE BLOOD ALCOHOL ANALYSIS SECTION
This section conducts quantitative analysis of alcohol levels in blood and urine.
Gas Chromatography
An accurate and expedient method of analysis, widely used today, is gas chromatography. The gas chromatograph is an instrument that separates complex mixtures of substances into component parts, identifying and quantifying them. The sample to be processed is placed in the injector port where it is vaporized (usually by burning), then swept into a column by a carrier gas. Each sample component emerges separately and is identified according to the time it has taken to traverse the column. The concentration of the component is sensed by a detector, which translates the information via electrical impulses, which are recorded on a graph. The column is operated isothermally or by programmed heat. This instrument is also used to analyze organic substances, such as narcotics, paints, petroleum products, etc.
THE TOXICOLOGY SECTION
Toxicology is the study of poisons and their action on the living organism. It is a very complex science that is divided into two areas: clinical and chemical. Clinical toxicology deals primarily with the recognition of poisoning symptoms, remedial treatments, and actions of poison in the body. Chemical toxicology focuses mainly on the detection of poison in stomach contents, blood, etc. The two areas of study naturally will overlap in a criminal investigation. A Toxicology Section in a police laboratory can normally conduct the following test for: elements is possible by studying the lines according to their respective locations. Determination of quantity is made according to the intensity of the lines.
LATENT PRINT SECTION
The latent print analysis of this section provide the field investigator with the following services:
1. Searches for, developers, photographs, and lifts latent prints at the scene of investigations.
2. Compares suspect’s prints with the latent prints obtained from crime scenes.
3. Takes plaster casts of footprints, tire tracks, etc.
4. Conducts fingerprints examinations of various items of evidence (e.g., guns and other weapons, paper, glass, metal etc).
5. A service available to investigators is a computer terminal that records fingerprints electronically, without ink or smudges. The fingerprints are captured by an optical disk, when the finger is pressed on the screen those in the state and federal files.
QUESTIONED DOCUMENT SECTION
This section conducts examinations and comparisons of forged and questioned documents (see figures 6-7 and 6-8). It also examines and compares handwriting exemplars (samples) made by suspects with handwriting on questioned documents; examines and compares exemplars made on typewriters and check protectors for comparison with questioned documents; and restores or deciphers altered, obliterated or erased writing. The physical matching of cut or torn paper of various types is also conducted by the questioned documents examiner.
Functions
The Questioned Documents Section is responsible for examining and comparinf forged or questioned documents, including:
Anonymous letters
Bills of sale
Checks
Holdup notes
Hotel registers
Narcotic Prescriptions
Pawnshop tickets
Receipts
Traffic citation signatures
Typewritten documents
Wills
FORENSIC PHOTOGRAPHY SECTION
This section performs a very critical service to criminal investigation. Through the use of forensic photography, many items of physical evidence, that are the prime incriminating factors in cases, are graphically depicted in trial courts. (See “Physical Evidence Examples”in Chapter 5 and figures 6-9).
Services Performed:
Crime scene performs documentation and recording
Physical evidence still photography and videotaping
Infrared, ultraviolet and infrared-luminescent photographic examination
Trace evidence photography
Aerial photography
Image enhancement techniques
Specialized identification and surveillance photography
Crime reconstruction, reenactment, etc., via motion picture or videotape procedures
A new forensic camera custom built by the Bureau of Organized Crime and Intelligence, California State Attorney General’s Office. The camera is contained in a briefcase; one corner contains a lens that captures images and transmits them to a remote television via microwaves.
POLYGRAPH SECTION
This section is responsible for the instrumental detection of deception. Note: There is no instrument that detects lies. The instrument commonly called a lie detector is actually a scientific diagnostic instrument (similar to the electrocardiograph) and is referred to in many police circles as the polygraph. A competent examiner can diagnose truth or deception.
Theory of the Examination
It is based on the emotion of fear.
Fear of detection by an untruthful subject will cause physiological changes to occur in the subject’s body at the point of deception.
Physiological changes can be diagnosed by a trained, competent examiner.
The subject must have something to gain or lose by submitting to the examination.
Components of the Polygraph
The pneumograph component: records changes in respiration.
The galvanograph component: records changes in the electrical resistance of the skin.
The cardiosphygmograph component: records changes in blood pressure and pulse rate.
The kymograph components: move the chart paper at the timed rate of speed, under the pens of the other three components.
Basic Uses of the Polygraph
The polygraph is an excellent aid and a valuable tool if properly utilized during the conducting of an investigation.
The polygraph, however, will never be able to take the place of good, measure, upon the thoroughness of the investigation prior to having a subject take the examination.
In criminal investigation, examinations will be conducted upon suspect, victims, witnesses and informants.
