GSR Particle analysis: A silent tool to criminal justice


“You have the Answer. Just get quiet enough to hear it”
The Criminal Justice Delivery System is the user of Science which delivers assistance in accordance with the demand of court. Science discovers and interprets the silent tools which are left behind by the offender unknowingly. GSR is one of those efficient element which helps to create a linkage between the crime and the criminal. Discharging from gun it falls on the persons and places involved. Thus GSR particles are to be collected and analysed within reasonable time to prove a gun firing. This paper explores different characteristics, composition, analysis technique and forensic significance of GSR. This information about GSR is a productive source of ideas, underscoring the need for participatory invention and implementation of GSR as a helping hand to the Criminal Justice.

Introduction: –

Chemical particles which are customarily referred to as Firearm Discharge Residues can also be expressed as Gun Shot Residues (GSR). GSR is discharged due to the chemical reaction of powder in a high temperature which is caused by the friction between bullet, barrel and explosion of primer. GSR particles may be traced on the hands and clothing of the shooter, they may fall on the target depending on the range of firing and other conditions. GSR particle may be found on the belongings of the shooter as well by transmission of particles depending on firing range. In cases of suicide, GSR particles are mainly found in shooter’s hand and, the presence of unique GSR particles can ensure the involvement of a person in a gun firing. Lead, Antimony, Barium and Aluminium is the chemical compounds which can be found in discharged GSR. Samples are taken from the suspected places to ensure the presence of GSR.
The importance of GSR as an efficient evidence is still being neglected especially in India where gun violence is an increasingly miscellaneous issue. Many of the cases related to firearms remain unsolved after decades and decades. In India, the gun violence cases are, very often, shut down slowly without proper investigation of GSR particles in the crime scene. The reasons behind the ignorance are mostly deficiency of properly trained personnel, corruption, politics etc. In the current legal studies, the basic knowledge of forensic science is not compulsory in many institutions.

GSR classification and their forensic significance:-

The important applications of Particle analysis are mostly related to the phenomenon of Dispersion of Particles in different directions. Particles disperse mainly in three directions :
1. Down Range.
2. Backward direction
1. Lateral direction
Down range dispersion help in estimating range of fire (e.g. Close ranges and beyond) and identification of bullet / projectile marks. Backward particles are analysed for Shooter Identification or handling a discharged firearm. Laterally dispersed particles are examined for presence of a person in proximity with the Shooter during discharge. Detection of particles in a bag, or any belongings suggests the involvement of the person with legal or illegal discharged Firearm(s). The backward, downrange and lateral particles are connected with discharging of firearms, and, therefore, come under 302 ANDA IPC or allied acts. GSR particles can also be considered as evidence of carrying illegal firearms or firearms illegally which comes under section 25, The Arms Act, 1959.
GSR produced during firing are further classified based on the range of firing as follows –
1. GSR produced in close range firing causes dust ring, burning, blackening and tattooing. The burning of skin is accompanied in due to the reaction with Carbon Monoxide which is also a product of combustion (GSR).
2. GSR produced in distant range firing contains no tiny metallic particles, no powder pattern is available. Metallic parts are produced during travelling through the barrel and thus appear on the surroundings of entry wound on the target.
3. GSR produced in contact firing causes GSR formation around the target or around the shooter depending upon the nature of firing. The entry area has projectiles and GSR can also be found in clothes and other garments of the victim, which act like intermediate targets.
4. Dispersed GSR particles are scattered in the air. Being light particles, they present in the air for a long time. They may be transferred to a surface which comes in contact with that air, or the surface which already contains GSR. Dispersed GSR particles may also be transferred to intermediate targets, other than clothes.

Composition of GSR :-
• Inorganic Components of Smokeless Powder
The inorganic materials in modern smokeless powders and primers which forms GSR can arise from several substances which are mentioned below:
Originating substance Produced components
Primers Lead, Barium, Antimony
Propellants Nitrites, Nitrates and Carbon monoxide (it gets absorbed by skin and flesh which causes bright red marks), Carbon particles.
Jackets Copper, Zinc and Nickel (mostly shells are coated with Nickel)
Barrels Iron
Bullet Lead
• Organic Components of GSR
Originating substance Produced components
Propellant Nitrocellulose, the parts which are not burnt or semi-burnt.
Organic lubricants Organic remains
Double base propellants The semi-burnt parts of Nitro-glycerine
Plasticizers Organic materials used as plasticizers are also detected as GSR.

GSR collection process:-
Dry Methods of Collection of GSR:- this process is followed by the officers to sample shooter’s hands, face or clothing by using a kit which contains following items;

Aluminium stub: – 2 aluminium stubs are present which can be of two types, i.e. 1 inch diameter stub (mostly used to sample GSR from hands and face), ½ inch diameter stub (mostly used to sample GSR from clothing and suspected objects). These stubs are covered with a double-sided tape. The stubs are pressed gently on the places where GSR is expected. Having adhesive of the surface the stub collects all the dirt including GSR particles.
The gloves: – after washing hands the gloves are to be used to continue the process of sampling.
Instruction sheet: – an instruction sheet is given to let the users know the way to use the kit.
Collection of Organic Residues:-
1. The evolution of the organic component of GSR is obtaining significance day by day. Some of the techniques of organic GSR collection are discussed briefly:
2. Swabbing technique: – A clean piece of cloth or filter paper, moistened with an organic solvent (acetone, alcohol etc.) is swabbed on a surface containing. The swabs are collected and GSR is extracted.
3. Tape lifting technique: – the surface containing GSR is taped with an inert tape having 2-3 cm width to pick up all dirt including GSR(both organic and inorganic). This technique is widely accepted because this technique collects both organic & inorganic GSR as well can be executed quickly.
4. Vacuum Lifting Technique: – This technique is mostly useful for collecting of GSR from clothes. The material extracted on the filter dust is extracted with a suitable solvent for further analysis.

GSR particle analysis and GSR identification:-
Chemical analysis:-

1. Sodium Rhodizonate Test: The test is carried out by lightly pressing a filter paper moistened with 0.1N Hydrochloric Acid (HCl), over the barrel hole. The filter paper is then dried using a hot air blower and examined with the help of 880 ammonia solution, Sodium Rhodizonate and HCL. This test can be used for the detection of barium.
2. Walker Test for Nitrites: This test is carried out for the detection of nitrites in the semi-burnt and unburnt propellants. In this test, a photographic paper, 5% 2 – naphthylamine – 4, 8 – disulphonic acid, 20% Acetic Acid is required to carry out this test. Many compounds (urine, face powder, fertilizers) other than nitrocellulose propellants can also give a positive result.
3. Griess Test: This is very similar to the Walker test. But the main reagent which is used instead of 2 – naphthylamine – 4, 8 – disulphonic acid is naphthylamine. This reagent gives orange spots. This test is also carried out for detection of propellant particles in range of firing estimations.
4. Marshall Test: This test is mainly used for detection of propellant particles in range of firing estimations.
5. Tewari Test: 1 gm. of Antazoline Hydrochloride (2 – N- benzyl aniline methyliminazoline hydrochloride), concentrated HCl, Antazoline solution is needed to carried out this test. This technique is mainly used for range of firing estimations by analysing propellant particles.
6. Lunge Reagent: This test was originally the ‘Dermal Nitrite Test’ used for the proof of firing a weapon. 0.25% solution of Diphenybenzidine, concentrated Sulphuric Acid is required to carry out this test.
7. Harrison and Gilroy Reagent: This reagent is mostly used for the identification of GSR on hand swabs, it can also be utilized just for range of firing estimations once the particles have been extracted from the garment.
8. Di-thio-oxamide (DTO) Test: This test helps to detect Copper and Nickel, and can be used for the determination of bullet entry and exit holes for fully jacketed gilding metal (Cu/Zn) and cupro-nickel (Cu/Ni) bullets. With DTO, copper generates a very dark -green coloration, nickel a pink to violet coloration and cobalt a brown coloration. However, the presence of blood can indicate a false negative result.

Suggestions: –

The status in India regarding the implementation of GSR in legal system is not encouraging. The academic background is important. The Judicial officers in lower and higher levels in our System including the practicing lawyers mostly do not come from academic background of Science. Even though they are highly qualified and expert in their own Jurisdiction, the mind-set does not encourage welcoming Science and unconsciously gradually become passive towards science. The System as a whole should traditionally shift towards science. Proper implementation and relevance of GSR analysis method to detect the shooter is still to be developed and spread among the police officers as well as legal professionals who deals with this kind of gun violence cases every day. Special initiatives should be taken to make the Criminal Justice Delivery System aware of the importance of the Technique through Training and Awareness Programs at various levels including Judiciary and police. The Indian criminal justice system is yet to get the benefits from recent developed techniques of GSR analysis but the facility and equipment is limited in comparison with the advanced countries. In a country like India where justice system is being delayed due to the huge numbers of cases, corruption and politics, GSR should be more prioritised as an evidence which can provide proper direction of investigation.


Gun violence is one of the greatest threats to public health and social security of present time. Recent studies took notice of deaths from 1990-2016 in 195 countries and territories across the world. Based on IMHE aggregate data from homicide, suicide and accidental injuries, 2016, Brazil, United States, India has the most firearm related deaths . Application of Science and Technology in Criminal Justice Delivery System is ever increasing and the use of the same is unavoidable. Also, Science & Technology, particularly the technology is fast developing. Without having any basic knowledge about the concerned method or technique, the judiciary system will fail to appreciate the scientific report. Therefore, the technology will remain unutilised. A silent but important piece of evidence left behind in the scene of occurrence is the gunshot residue (GSR) which is generated while shooting a firearm. GSR is a heterogeneous cloud of hot vapours and micrometer particles originating from the explosion of a cartridge from a cartridge-case. These particles can be seen under the Scanning Electron Microscope only. GSR analysis therefore represents a significant analytical challenge, requiring a technique that can sensitively and non-destructively image and analyse individual particles down to 0.5 microns in diameter. The Justice seekers will be deprived from real justice. So, the knowledge of GSR is very important for not only Lawyers but also for judicial officials and allied personnel of justice delivery system including Police personnel. The present days and the days to come demand the basic and updating knowledge of Science and Technology in Justice Delivery System in absence of which the system will collapse someday. Lawyers having the basic knowledge can appreciate the report or shortcomings of the investigation in a better way which can be helpful for judgment or further necessary action. It can benefit the court for better interpretation and understanding within the framework of law with confidence which the unaware lawyers will obviously lack. The advantage lies in confidence, contribution and overall performance. The main contributing factors are, therefore, quick responses and test, quality assurance, reliability and confidence of the Court. It is may not be out of context to mention the famous statement of an eminent Justice of USA Supreme Court in a Science vs. Law debate, SCIENCE can make it GOOD , but it is up to The COURT how far they will accept the SCIENCE .


V.N. Sehgal, Forensic Ballistics, E PATHSHALA
Jenna A. Campbell, Analysis of Metallic Components of GSR from Various Types of
Ammunition and Firearms Utilizing an SEM-EDX, J. Mater. Sci., 2018, 10
V.N. Sehgal, Forensic Ballistics, E PATHSHALA
M.Chohra et al, Journal of Radiation Research and Applied Sciences, 8 SEM/EDX 407, 407-408 (2015)

Detection of Gunshot Residue on the Hands by Neutron Activation and Atomic Absorption Analysis, 19 J. Forensic Sci 3-4 (1974), pp. -, ISSN
El-Taher, Nuclear Analytical Techniques for Detection of Rare Earth Elements. Journal of Radiation and Nuclear Applications. 3. 10.18576/jrna/030107 Atef. 56 (2018)..
Final report on particle analysis for gunshot residue detection, AEROSPACE REPORT ATR-77(7915)-3

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