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Updated: Sep 1, 2023


Forensic science

Forensic science is a multidisciplinary subject used for examining crime scenes and gathering evidence to be used in prosecution of offenders in of law . Forensic science techniques are also used to examine compliance with international agreements regarding weapons of mass destruction . The main areas used in forensic science are biology , chemistry , and medicine , although the science also includes the use of physics , computer science geology , and psychology . Forensic scientists examine objects , substances ( including blood or drug samples ) , chemicals ( paints , explosives , tonic tissue traces ( hair , skin ) , or impressions ( fingerprints or tidemarks ) left at the crime scene . The majority of forensic scientists specialize in one of the science .

Evidence and trace examination .

The analysis of the scene of crime or accident involves obtaining a permanent record of the scene ( forensic photography ) and collection of evidence for further examination and comparison , Collected samples include biological ( tissue samples such as skin , blood , semen , or hair ) , physical ( finger nail shells , fragments of instruments or equipment , fibers , recorded voice messages , or computer discs ) and chemical ( samples of paint , cosmetics , solvents , or soil ) . Most commonly , the evidence collected at the scene is subsequently processed in a forensic laboratory by scientists specializing in a particular area . Scientists identify , for example , fingerprints , chemical residues , fibers , hair , or DNA left behind . However , miniaturization of equipment and they perform most forensic analysis at the scene of crime results in more specialists being present in the field . Presence of more people at the scene introduces a greater likelihood of introduction of contamination into the evidence . Moreover , multi - handling of a piece of evidence ( for example murder weapon being analyzed by many specialists ) is also likely to introduce traces of tissue or DNA not originating from the scene of a crime . It results in strict quality controls imposed on collection , handling , and analysis of evidence to ensure lack of contamination . For example , in DNA test it is essential that samples are stored at the correct temperature and that there is no contamination from a person handling a sample by wearing gloves and performing analysis in a clean laboratory .

Ability to properly collect and process forensic samples can affect the ability of the prosecution to prove their case during a trial . The presence of chemical traces or DNA on a piece of debris is also crucial in establishing the chain of events leading to a crime or accident .

A growing area of forensic analysis is monitoring of non - proliferation of weapons of mass destruction , analysis of possible terrorist attacks or breakup security . The nature of samples analyzed is wide , but slightly different to a criminal investigation . In addition to the already described samples , the scientists who gather evidence of mass destruction collect swabs from objects , water , and plant material to test for the presence of radioactive isotopes , toxins , or poisons , as well as chemicals that can be used in production of chemical weapons . The main difference from the more common forensic investigation is the amount of chemicals present in a sample . Samples taken from the scene of suspected chemical or biological weapon contain minute amounts of chemicals and require very sensitive and accurate instruments for analysis .

( i ) Biological traces . Biological traces are collected not only from the scene of crime and a deceased person , but also from surviving victims and suspects . Most common samples obtained are blood , hair , and semen . DNA can be extracted from any of these samples and used for comparaties analysis . DNA is the main method of identifying people . Victims of crashes or fires are often unrecognizable , but adequate DNA can be isolated and person can be positively identified from a sample of their DNA or their family's . DNA is taken for comparison . Such methods are being used in the identification of the remains in Yugoslav war victims , the World Trade Center attack victims , and the 2002 Bali bombing victims . Biological traces , investigated by forensic scientists come from bloodstains , saliva samples ( from cigarette butts or chewing gum ) and tissue such as skin , nails , or hair , Samples are processed to isolate the DNA and establish the origin of the samples .

( ii ) Chemical traces . - Forensic chemistry performs qualitative and quantitative analysis of chemicals found on people , various objects , or in solution , chemical analysis is the most varied from all the forensic disciplines . Chemists analyze drugs as well as paints , remnants of explosives , fire deberes shot residues , fibers , and soil samples . They can also test for a presence of radioactive substances ( nuclear weapons), toxic chemicals ( chemical weapons ) and biological toxins ( biological weapons) . Forensic chemists can also be called on in a case of environmental pollution to test the compounds and trace their origin .

( iii ) Physical evidence . - Physical evidence usually involves objects found at the scene of a crime . Physical evidence may include all sorts of prints like fingerprints , footprints , handprints , tidemarks , cut marks , tool marks , etc. Analysis of some physical evidence is conducted by making impression plaster , taking images of marks , or lifting the fingerprints from objects encountered . These serve later as a comparison to identify , for example , vehicle that was parked at the scene , a person that was present , a type of manufacturing method used to create a tool , or a method used to built building or harm a victim . An examination of documents found at the scene or related to the crime is often an integral part of forensic analysis . Such examination is often away to establish not only the author , but more importantly identify any alterations that have taken place . Specialists are also able to recover text from documents damaged by accident or on purpose .

( iv ) Identification . The identification of people can be performed by fingerprint analysis or DNA analysis . When none of these methods can be used then facial reconstruction can be used instead to generate a person's image . TV and newspapers then circulate the image for identification .

3. Other forensic scientists . Pathologists and forensic anthropologists play a very important part in forensic examination . They are able to determine the cause of death by examining marks on the bone ( s ) , skin ( gunshot wounds ) , and other body surfaces for external trauma . They can also determine a cause of death by toxicological analysis of blood and tissues . A number of analytical methods are used by forensic laboratories to analyses evidence from a crime scene . Methods vary , depending on the type of evidence analyzed and information that needs to be extracted from the traces found . If a type of evidence is encountered for the first time , a new method is developed .

Biological samples are most commonly analyzed by polymeraze chain reaction ( PCR ) . The results of PCR are then visualized by gel electrophores Forensic scientists tracing the source of a biological attack could use the new hybridization or PCR based methods of DNA analysis . Biological and chemical analysis of samples can identify toxins found . Imaging used by forensic scientists can be as simple as a light microscope , or can involve an electron microscope , absorption in ultraviolet to visual range , colour analysis or fluorescence analysis . Image analysis is used not only in cases of biological samples , but also for analysis of paints , fibers , gunshot residue , or other chemicals . Image analysis is often essential for an interpretation of physical evidence . Specialists often enhance photos to visualize small details essential in forensic analysis . Image analysis is also used to identify details from surveillance cameras .

New laboratory instruments are able to identify nearly every element present in a sample . Because the composition of alloys used in production of instruments , wires or bullet casings is different between various producers , it is possible to identify a source of the product . In some cases , chromatography alone is not an adequate method for identification . It is then combined with another method to separate the compounds even further and results in greater sensitivity . One such method is mass spectrometry ( MS ) . A mass spectrometer uses high voltage produce charged ions . Gaseous ions or isotopes are then separated in a magnetic field according to their masses . As some samples are difficult to analyze with MS alone , a laser vaporization method ( imaging laser ablation mass spectroscopy ) was developed to produce small amounts of chemicals from solid materials ( fabrics , hair , fibers , soil , glass ) for MS analysis . Such analysis can examine hair sample for presence of drugs or chemicals . Due to its high sensitivity , the method is of particular use inmonitoring areas and people suspected of production of chemical , biological or nuclear weapons , or narcotics producers . While charcoal sticks are still in use for fire investigations , a new technology of solid phase microextraction ( SPME ) was developed to collect even chemicals and does not require any solvent for further analysis .

A number of Government agencies ( for example the FBI ) are now armed with the portable instruments and can perform rapid forensic analysis in the field in a time shorter than it would take to transport samples to a forensic laboratory . States troops are equipped with similar instruments on board some and trucks , in order to quickly determine the presence of chemical or biological weapons on the battlefield .

Applications of forensic science - The main use of forensic science is for purposes of law enforcement to investigate crimes such as murder , fraud . Forensic scientists are also involved in investigating accidents such as train or plane crashes to establish if they were accidental or a result play . The techniques developed by forensic science are also used by the army to analyze the possibility of the presence of chemical weapons , explosives or to test for propellant stabilizers . Gasoline products often evaporate rapidly and their presence cannot be confirmed , but residues of chemicals , such as propellant stabilizers , are present for much longer indicating that an engine or missile was used .


Branches in forensic science .

The application of scientific knowledge and methodology to legal problems and criminal investigations . Sometimes called simply forensics , forensic science encompasses many different fields of science , including anthropology , biolog chemistry , engineering , genetics , medicine , pathology , phonetics , psychiatry , and toxicology . The related term criminalistics refers more specifically to the scientific collection and analysis of physical evidence in criminal cases . This includes analysis of many kinds of materials , including blood , fibers , bullets , and fingerprints . Many law enforcement agencies operate crime labs that per scientific studies of evidence . The largest of these labs is run by the Federal Bureau of Investigation .Forensic scientists often present expert testimony to Courts , as in the case of pathologists who testify on causes of death and engineer who testify causes of damage from equipment failure , fires , or explosions ,

Modern forensic science originated in the late nineteenth century , when European Criminal investigators began to use fingerprinting and other identification techniques to solve crimes . As the field of science expanded in scope throughout the twentieth century its application to legal issues became more and more common . Because nearly every area of science has a potential bearing on the law , the list of areas within forensic science long .

Forensic Medicine and Psychology - Forensic medicine is one of the largest and most important areas of forensic science . Also called legal medicine or medical jurisprudence , it applies medical knowledge to criminal and civil law . Areas of medicine that are commonly involved in forensic medicine are anatomy , pathology , and psychiatry . Many law enforcement agencies employ a forensic pathologist , sometimes called a medical examiner , who determines the causes of sudden or unexpected death . Forensic cologists , who the presence of poisons or drugs in the deceased , often help forensic pathologists . Forensic odontologists , or dentists , analyze dental evidence to identify human remains and the origin of bite marks . Forensic medicine is often used in civil cases . The cause of death or injury is considered in settling insurance claims or medical malpractice suits , blood tests often contribute to a Court's decision in cases attempting to determine the paternity of a child .

Mental health and psychology professionals have contributed great deal to the legal understanding of issues such as the reliability of eye - witness testimony , responsibility for criminal behaviour , and the process of decision making injuries . These professionals include those with a medical doctor such as psychiatrists , neurologists , and neuropsychologists , as well as individuals without a medical degree , such as psychologists .

Mental health professionals are frequently consulted in civil and criminal cases to help determine an individuals ' state of mind with regard to a criminal validity of testimony before a Court , or an individuals ' competence to stand trial or make a legal decision . Their input may also be vital to legal procedures for deciding whether to commit a person to an institution because of mental illness , or to allow a person to level an institution for those who are mentally ill .

Forensic neuropschology is a specialized area of forensic medicine that applies that functioning of the nervous system and brain to legal issues involving mind and behavior . Equipped with an improved understanding of how the brain works and influences behaviour , neuropsychologists have increasingly been asked to provide testimony to Courts attempting to determine whether a criminal act is a result of a nervous system dysfunction . They also testify as to the reliability of witness testimony given by victims of crime , the competency of individuals to stand trial , the likelihood that the condition of mental retardation or brain injury predisposed an individual to commit a crime , the possibility that an individual has verifiable memory and various aspects of dementia's and other brain disorders caused by AIDS , head injuries , and drugs , alcohol , and other chemicals .

In civil cases , the work of neuropsychologists has been used to determine whether a defendant's wrongdoing caused a plaintiff's injury . In family Courts , neuropsychologists assess brain damage in children who have been physically abused .

Forensic psychologists provide expert testimony that touches on many of the same areas as that given by forensic psychiatrists and neuropsychologists . In addition , psychologists consult with the legal system on issues such as correctional procedures and crime prevention . In 1962 , Court of appeals issued . an influential decision that established the ability of a psychologist to testify as an expert witness in a federal Court of law . Before that time , expert testimony on mental health was largely restricted to psychologist .

What is a forensic scientist ?

A forensic scientist examines physical evidence and then testifies about the results of their finding in Court . They are in fact defined by the expectation that they may give expert testimony about their examinations and further provide interpretations or opinions under oath . As explained in Thornton ( 1997 ) : " Forensic " comes to us from the Latin forensus , meaning " of the forum . " In Ancient Rome , the forum was where Governmental debates were held , but it was also where trials were held . It was the Courthouse . So forensic science has come to mean the application of the natural and physical sciences to the resolution of conflicts within a legal setting . The single feature that distinguishes forensic scientists from any other . scientist is the certain expectation that they will appear in Court and testify to their findings and offer an opinion as to the significance of those findings . The forensic scientist will testify not only to what things are , but to what things mean .

Forensic science is science exercised on behalf of the law in the just resolution of conflict . A true forensic scientist is not a policeman , nor are they partial about the outcome of their examinations . They are objective investigators of scientific fact . Subsequently , a forensic scientist may work in a state run crime lab , or they may work in private practice .

The role of forensic scientist in detection of crime - The scientific examination of a forensic scientist adjoins a missing link or strengthens a weakly in the chain of investigation by furnishing an impartial and evidence , thereby helping the Court to come to a conclusion regarding the criminals and their punishments .

The field of study or examination of forensic scientist is very wide , divisible and unpredictable . Generally the duties and responsibilities of forensic scientist are very hazardous , onerous and risk bearing .

1. Because they are to deal with the material exhibits pertaining to various nature of crimes such as murder , rape , blood , saliva , firearms , ammunitions , explosives , and explosives substances , liquor , hashish , opium , adulterated petrol , kerosene , diesel , etc. other chemical vehicles involved in accidents , various types of paints . Weapons , and used in burglary , arson , etc. ,

2. different types of poisons and poisons and poisonous substances , hair , skeletal remains and other plant or animal remnants . and documents alongwith the photographic analysis of all materials exhibits .

Apart from these , forensic scientists are also to examine the forged signatures Any material exhibit encountered in the way of investigation needs to be thoroughly examined to prove or disprove its association a particular crime or criminal . Practically the forensic scientist are to examine the material exhibits connected with various nature of crime covering all sections of IPC and other relevant acts and laws of the land .

Unlike other research and analytical materials , forensic scientists are required to work with limited quantity and amount of materials generally left behind or carried away by criminals .

Let us discuss first about the forensic physicist . Generally , the material exhibits which are obtained at the scene of crime are examined by the scientist of this division . Besides comparative studies of various impressions and marks of tools etc. , used in commission of crime are also made in this division . Determination of forced engine or chassis marks or restoration of an erased number upon metallic dates are determined by the scientist of this division . Analysis of paints and glass articles , stamp impressions of forest authorities can be examined by these scientists to establish the facts for the determination of clues of commission of crimes and criminals .

Secondly the scientist of forensic chemistry are also equally busy determining clues of crime and detection of criminals by their various methods of analysis . For instance it is the forensic chemist who has to determine purity of petrol , diesel and kerosene from samples . They are also to determine the quality of liquor , opium , ganja and other chemicals , analysis of explosive and the like . From their various methods of analysis , they have to establish facts basing upon which the investigating officers can detect the clues of a particular crime .

Forensic biologists have also been playing an important role in examining biological exhibits oriented with crime . It is the biologist who has to analyze the biologist material exhibit starting from a micro organism to a higher plant or an animal and also their parts and products . From the skeletal remains a biologist has to determine the sex , origin , stature , and age of the deceased . He is to identify from the skull by using superimposition method and thereby help the investigating authority in coming to a conclusion with the regard to a particular crime . In case of a suspected death case , the biologist is to ascertain the cause of death . He is also to analyse various poisonous plant material in cases where plant poison is administered in the commission of crimes .

A Serologist plays equally important role in establishing facts in respect of various crimes . In case of a murder where knife and other weapons are involved , it is the serologist who is to ascertain whether the particular weapon is stained with human blood or not . From the findings of a serologist , the investigating officer can get a definite clue in a particular case , depending on which the investigating officer can identify the culprit of the crime . It is the Serologist who has to establish the facts of disputed paternity cases by testing the blood group in question .

Now , coming to the ballistics branch of forensic science it may be stated that a ballistic expert is the only person who ascertains whether a particular fire arm was used or not while committing a crime . He is also to examine the types of fire arms and ammunitions used in commission of a crime . He has also to establish the facts with regard to firing ranges , distance , direction , and angle of firing . After obtaining the opinion of a ballistic expert the investigating officers can come to a reasonable conclusion in respect of a particular crime . Apart from the different fire arms and ammunitions a ballistic expert is also to examine the explosive substances which are nowadays very often used for committing heinous crimes .

A toxicologist determines the clues of the crime in which poison is used . In any such case , be it accidental , suicidal or intentional , a toxicologist analyses the viscera and other relevant materials from which he establishes the quality and quantity of poison used . From the report of a toxicologist , the investigating officer can usually obtain vital clues for detecting the criminals involved . Similarly , the Court also gets positive evidence for coming to a conclusion in any particular case .

A document expert examines various types of documents directly or indirectly involved in a forgery case . The forgery cases may be of different types , but all these are examined by the handwriting expert . From the report of a document examiner , the investigating agency can definitely detect the real culprit of a particular case . Apart from the forged signatures or documents , a handwriting expert often gives opinion on typed papers , time of writing and the age of the ink used for writing a questionable documents . So the opinion of a handwriting expert also helps the Court to reach a conclusion in meeting the ends of justice .

Like all others branches of science , personnel of the photography division a play a vital role in determining clues of crimes and detecting the criminals . It da crime by their Photographic evidence . In case of a crime where the facts of the forensic photographer who establishes the connecting link of various clues ere is involved , it is only the photographic evidence by which the facts of eure can be established with any degree of precision . Thereby they are also Ang the Courts to come to a definitive opinion with regard to the case .

Droplets of human blood . In addition to analyzing for DNA , the droplets are round and show no spattering , indicating they impacted at a relatively slow velocity , in this case from a height of two feet

People can be identified by their fingerprints .

People can also be identified from traces of their DNA by DNA fingerprinting

Forensic medical - What is the difference between a medical examiner and a coroner ? Medical examiners and coroners are two different groups that provide a similar service to their communities Coroners are part of an older system whose origins date back to England many centuries ago , and are usually elected by individuals . Coroners contract with physicians to provide autopsies and medical expertise to support their investigations . In contrast , the medical examiner system is an American creation approximately a century old . Medical examiners are almost always appointed to their positions , and should be physicians with training in medico - legal death investigation .

Forensic photography . The first thing that needs to be done after securing the crime scene is photographing it . This creates a permanent record of the condition of the crime scene , one that is incontestable . First , take a picture that shows where the scene is a shot with a street sign with the crime scene location in the background . Take pictures of the areas around the crime scene , aleys , dumpsters , rear areas , neighbouring structures and even the structures across the street .

What items are photographed at a crime scene ? Bullet casings ; photograph as a group and photograph individually . Photograph any dropped items , foot prints or animal tracks . If a homicide , photograph the body or bodies . Photograph any tool marks , bite marks or skin impressions . Basically , anything that might be evidence is photographed .

Video surveillance cameras . - Types of cameras available for video surveillance - You have a broad range of video surveillance cameras available to you . Understanding the different kinds will make it easier to determine which one suits you best :

  • Fake security cameras - These are not actual cameras . They are a very inexpensive alternative to purchasing an actual system . While these cameras can act as a deterrent should something happen , you will not have a record of it . •

  • Covert surveillance cameras - These cameras look like regular items . A wall clock in a small store a teddy bear in a baby's room , a potted plant by the front door each one of these could very easily be a surveillance camera . You can record without anyone knowing it . •

  • Wireless security cameras - These offer more flexibility in set up . They are easy to install , can be moved easily , are often small , have no tell - tale wires , and are very discreet . •

  • Wired surveillance cameras - These cameras are appropriate for permanent setup . If you have one location that you would like to constantly monitor and will not need it to be changed a wired cameras is an option . Some may have to be professionally installed .

  • Night vision security cameras - These are ideal for any low - light areas , not just for the height time . The camera records in black and white in order to capture images best .

  • Home surveillance cameras - When you buy a setup for home , you get a helpful system that often includes such bonuses as timers for your lamps and motion sensors to go with the wireless camera .

Night vision device -

A night vision device ( NVD ) is an optical instrument that allows images to be produced in levels of light approaching total darkness . They are most often used by the military and law enforcement agencies , but are available to civilian users . The term usually refers to a complete unit , including image intensifier tube , a protective and generally water resistant housing , and some type of mounting system . Night vision devices were first used in World War II , and came into wide use during the Vietnam War .

Forensic toxicology -

Toxicology is important not just or an investigation in which foul play is suspected . It is equally essential for determining accidental deaths and suicides and even for substance abuse while on the job . A toxicologist may be called on to test for anything from arsenic to poisoned gas to GHB to prescription drugs .

A popular poison for suicide is carbon monoxide from a car engine although drug overdoses or mixed doses of domestic medications are also widely used . Accidental deaths can result from overdoses of drugs such as opium , hyoscine . morphine and heroin . Examples of poisons that have been commonly used for murder are aconitins , atropine , strychnine , thallium , antimony , arsenic and cyanide

The history of forensic toxicology goes back about 200 years , but before reviewing it , let's first define what this branch of science actually is . Technically speaking , John Brenner's Forensic Science Glossary defines toxicology as the study of poisons , but it also covers the detection of foreign substances in the body that can have a toxic effect , such as alcohol , industrial chemicals , poisonous gas , illegal drugs , or drug overdoses .

Digital forensics .

Nearly all " white collar crimes today involve the computer either as a tool in enabling the crime or as a target of the crime . Digital forensics is the discovery , analysis , and reconstruction of evidence extracted from any element of computer systems , computer networks , computer media , and computer peripherals that allow investigators to solve the crime . In the battle against malicious hackers , digital forensic investigations are performed in support of various objectives , including timely cyber attack containment , perpetrator location and identification , damage mitigation , and recovery initiation Computer forensics deals with gathering evidence from computer media seized at the crime scene . Network forensics gathers digital evidence that is distributed across large - scale , complex networks . while current commercial intrusion analysis tools are inadequate to deal with today's networked , distributed environments .

Forensic investigation of crime and scientific services of CBI of India .

Existing examination facilities - The CFSL ( CBI ) , New Delhi has the following divisions , which are providing forensic support services to the various Investigating Agencies in scientific analysis of exhibits and collection / detection of relevant physical clues from Scene ( s ) of Crime . The scientists of the laboratory are put to rigorous training's in India and abroad in order to upgrade the existing forensic skills and to induct innovative technologies in the field of Forensic Science .

  • Ballistics Division

  • Biology Division

  • Chemistry Division

  • Computer Forensic Division

  • DNA Profiling Laboratory

  • Document Division

  • Finger Print Division

  • Lie Detector Division

  • Photo & Scientific Aid

  • Physics Division •

  • Serology Division

  • Scientific Aid Unit ( Chennai )

Ballistics division

The Ballistic Division is equipped with the latest sophisticated instruments and necessarily expertise to handle cases of firearms and explosives . The Ballistics work involves examination of firearms to determine the nature and type of weapons used in the crime , range of firing , linking fired bullets , cartridge cases with the suspect weapons and checking of mechanism of the weapon for the evidence of accidental discharge .

Biology division .

The biological characteristics and other related tests of biological samples are carried out in Biology Laboratory . The articles / exhibits forwarded include blood samples , cloth , soil , hair , semen , bones , botanical products such as fiber , starch , grain etc. , from the scene of crime / victim / suspects .

Chemistry division .

Chemistry Division Consists of Toxicology , Narcotics and General Chemical Analysis sections . The division is equipped with high - tech analytical equipment's i.e. , High Performance Thin Layer Chromatography ( HPTLC ) and Gas LiquidChromatography ( GLC ) System etc. , and undertakes chemical analysis of exhibits such as viscera , biological fluids , trap cases , dowry death cases , petroleum products , acids and various other miscellaneous exhibits referred by the investigating Agencies . Viscera including biological fluids are examined for poison detection in cases of homicides and suicides

Computer forensic division .

Computer Forensic division started functioning from January 2004. The division provides facility for examination of off - line Computer / digital storage media such as Central Processing Unit , Hard Disc Drives , Compact Discs , Floppies , Flash / Pen / Thumb drive and other similar devices with USB connectivity . Its main objectives are preservation , identification , extraction and documentation of computer evidence in various Computer related crimes ie . , e - mail tracing , pornography , human trafficking , corporate frauds etc. , forwarded to the laboratory . The deleted data can be retrieved without tempering date & time tag by use of various professional hardware / software tools validated by Courts of Law . Cross - validation of results through the use of multiple tools and techniques is in the standard protocols of the laboratory .

DNA profiling laboratory

The state - of - the - art DNA Profiling Laboratory of CFSL ( CBI ) . New Delhi is equipped with latest requirements as per the demand of the technology , has been brought into operation since the year 2006 the laboratory carries out Autosomol STR analysis and Y STR analysis of the genomic DNA obtained from any type of evidence samples requiring DNA profiling with respect to the crime cases like establishment of relatedness , disputed paternity , sexual assault , missing person , unidentified dead bodies with absolute accuracy .

Document division .

The Document Division is encountered with broad spectrum of problems pertaining to white collar crime like examination of handwriting and signatures , detection of forgery , detection and decipherment of erased , obliterated writings , decipherment of postal cancellation seals , rubber seals etc. , examination of printed matter , type scripts , decipherment of invisible ink , examination of charred documents , determination of sequence ( relative age ) of two intersecting pen inks . Throughout the year , the division furnished expert opinion on documents referred by CBI , Delhi Police , Railways and various other Govt . of India departments including the Judiciary . The Experts of the division tender evidence in various Courts throughout India and impart training by way of delivery of lectures to the trainees of CBI Academy , NICFS , Banks , Railways , Universities etc. The Document Division has recently added latest state - of - the - art instrument called VSC - 5000 for quality examination of questioned documents . Finger Prints division provides service to all branches of CBI with reference to examination of questioned thumb impressions , crime scene visits for chance prints , developments of latent prints , preparation of specimen ten digit finger prints of accused / suspects & deposition in Courts Delhi Police and judicial Courts and other Central Government Departments also tap the available resources for similar purposes in important crime investigation .

Lie detector division

The Lie Detection division renders valuable polygraph aids in number of important investigation conducted by CBI , Judiciary , Delhi Police and other law enforcement agencies . The Lie Detection division maintains latest version of computerized polygraph equipment's . Lie detection technique is based on the principle of psychosomatic interactions of an individual , i.e. , a change in the person's consciously held feelings produces a psychological defence reaction in the form of physiological changes in his blood pressure , pulse rate , respiration and electro-dermal response ( GSR ) . Fear of detection and entrapment induces a person to conceal the facts and this produces uncontrollable physiological reactions , which are precisely measured by Polygraph .

The objectives of the Lie Detection technique are :

1. To verify the statements of suspects , witnesses & complainants .

2. To economise and accelerate the process of investigation by screening innocent persons where a large number of suspects are involved .

3. Scientific interrogation of suspects in white - collar crime .

4. To corroborate the findings of investigation by Investigating Officers .


Photo & scientific and division . -

Physics division . - In Physics , division different types of examinations have been carried out like examination of paint , glass , soil , fibers , metallic pieces , threads and ropes , cloth pieces , struggle mark and cut - marks on cloth , knot examination , examination of metallic seals , postal seals , and wax seals , deciphering of erased chassis and engine number of vehicles , registration plate of vehicles , examination of tool marks etc. The Physics division is also carrying out the examination of telephonic and direct recording in respect of Speaker Identification . A very advanced version of computerized Voice Spectrograph namely Computerized Speech Lab Model CSL - 4500 has been acquired and is being used for analysis of Speaker Identification cases .


Scientific and unit ( Chennai )

The scientific Aid Unit ( Chennai ) provides the facilities of document examination as provided by the Document Division of CFSL . New Delhi , like examination of handwriting , signatures , typescripts , rubber stamp impressions , seal impressions , examination of counterfeit currency notes and lottery tickets , determination of interpolation , substitution , addition , over - writings , decipherment of the mechanically and chemically erased writings , decipherment of invisible ink reconstruction of the charred and burnt documents , determination of the order of the sequence of the strokes at the point of inter - sections , examination of the torned or serrated edges of paper and comparison with their counterparts , determination of the absolute or relative age of the documents , examination of ink , paper and writing implements etc.


Definition of forensic science

Forensic science is the use of science in the service of the law . Sciences used in forensics include any discipline that can aid in the collection , preservation and analysis of evidence such as chemistry ( for the identification of explosives ) , engineering ( for examination of structural design ) or biology ( for DNA identification or matching ) . A forensic scientist is expert in any technical field and can provide an analysis of the evidence , witness testimony on examination results , technical support and even training in his or her specialized area .

it can help to establish the guilt or innocence of possible suspects . Forensic evidence is also used to link crimes that are thought to be related to one another .

For example , DNA evidence can link one offender to several different crimes or crime scenes ( or exonerate the accused ) . Linking crimes help law enforcement authorities to narrow the range of possible suspects and to establish patterns of for crimes , which are useful in identifying and prosecuting suspects .

Forensic analysis is usually carried out by experts working individually or in teams . Advanced techniques often require laboratories where the investigative conditions can be carefully controlled and monitored . Private laboratories and Government agencies support small and large forensic labs . Analysis of forensic evidence is used in the investigation and prosecution of civil and criminal proceedings . Forensic scientists also work on developing new techniques and procedures for the collection and analysis of evidence . In this manner , new technology can be used and refined not only to keep forensic scientist on the cutting edge of science , but to maintain the highest standards of quality and accuracy .


The Indian scenario .

Let us first the legal aspect of forensic and medical evidence in the India . As per Section 45 of Indian Evidence Act , 1872. When the Court has to form and opine upon a point of foreign law or science or art , or as to identity of handwriting or finger impressions , the opinions upon that point of persons specially skilled in such foreign law , science or art , or in questions as to identity of handwriting or finger impressions are relevant facts . Such persons are called experts . Further , as per Section 46 of Indian Evidence Act , 1872. It is stated that facts , not otherwise relevant , are relevant if they support or are inconsistent with the opinions of experts , when such opinions are relevant .

Thus the ingredients of Section 45 and Section 46 are highlights that :

1. The Court when necessary will place its faith on skills of persons who have technical knowledge of the facts concerned .

2. The Court will rely the bona fide statement of proof given by the expert concluded on the basis of scientific techniques .

3. The evidence considered irrelevant would be given relevance in eyes of law if they are consistent with the opinion of experts .

Thus , we see that expert evidence helps the Courts to draw logical conclusions from the facts presented by experts , which are based on their opinions derived by their specialized skills acquired by study and experience . Hence , experts are routinely involved in the administration of justice particularly in criminal Courts . Highlighting the situation in the most commonly sought after experts

The Medical experts

In India , we have adversarial system of justice administration and ordinarily medical evidence is admitted only when the expert gives an oral evidence under an oath in the Courts of law expect under special circumstances like

( a ) When evidence has already been admitted in a lower Court :

( b ) Expert opinions expressed in a treatise ;

( c ) Evidence given in a previous judicial proceeding :

( d ) Expert cannot be called as witness ;

( e ) Hospital records like admission / discharge register , birth / death certificates etc ..

In , India , it is a common perception that lot of time and effort is required to record evidence and therefore by enlarge members of the medical profession does not like to involve in medico - legal cases . Some of the possible reasons put forward for this perception are :

( a ) Undue time consumption ;

( b ) Repeated adjournments ;

( c ) Lack of work culture in the Courts

Hardly , any scientific data is available to support or refute this perception in relation to medical evidence . Therefore , it was planned to undertake a study to analyze the quantum of time and effort put in by medical experts to get the evidence recorded in criminal Courts and other issues related to it .


Forensic & Criminal Psychology. Criminal Behaviour :

Before talking about what forensic and criminal psychology is , we must define criminal behaviour first . Criminal behaviour suggests a large number and variety of acts . Andrew and Bonta ( 1998 ) suggest four broad definitions of criminal behaviour and the acts and behaviours that fit within these domains . These four areas are legal criminal behaviour or actions that are prohibited by the State and punishable under the law , moral criminal behaviour which refers to actions that violate the norms of religion and morality and are believed to be punishable by a supreme spiritual being social criminal behaviour which refers to actions that violate the norms of custom and tradition and are punishable by a community and finally psychological criminal behaviour that rear to actions that may be rewarding to the actor but inflict pain or loss on others . It is criminal behaviour that is anti - social behaviour .

It is difficult to define criminal behavior as ideas of what is considered immoral , unconventional , illegal or antisocial is not stable over time or place . Delinquency must be distinguished from criminality . Delinquency is defined as behaviour that is illegal , immoral or deviant with respect to societal values . Criminality on the other hand is defined as a breaking of existing laws , there is little or no confusion as to what constitutes illegal and legal behaviours .

When measuring criminal behaviour we are trying in a way to predict future criminal behaviours . We may measure criminal behaviour by arrests and charges , however , not everyone charged is found guilty . We can also measure the amounts of convictions and incarcerations Therefore , when we study criminal behaviour we typically study what is known about persons who have been defined as criminals throughout the criminal justice system .

Estimates of actual crime rates are usually obtained from official sources , yet different sources may yield different estimates . generally categorize crimes by type of crime and offender characteristics such as age , gender , race and location .the best single predictor of recidivism is number and type of previous criminal offences , and these rates will vary due to age gender and type of crime .

A risk factor for criminality is anything in a persons psychology , developmental or family history that may increase the likelihood that they will become involved in some point in criminal activities . A protective factor is anything in a persons biology , psychology , developmental or family history that will decrease the likelihood that they will become involved in criminal activity .

Brownfield and Thompson found that boys who had committed delinquent acts were more likely to have friends who had done so as well . This increased when the friend was considered a " best friend " . As well , risk factors can be divided into the various childhood time periods that they may occur and increase later criminal activity .

The " cycle of violence hypothesis " predicts that abused children will become abusers and victims of violence will become violent offenders .



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