Forensic Chemistry and Toxicology - Gunshot Residue - CARCAR CITY COLLEGE

Republic of the Philippines ***CARCAR CITY COLLEGE*** Luanluan Street, Poblacion I, Carcar City, Cebu Tel \# 487-0063/487-9077 +-----------+-----------+-----------+-----------+-----------+-----------+ | **Subject | **:** | Forensic | **Discuss | **:** | 3 |...

Republic of the Philippines ***CARCAR CITY COLLEGE*** Luanluan Street, Poblacion I, Carcar City, Cebu Tel \# 487-0063/487-9077 +-----------+-----------+-----------+-----------+-----------+-----------+ | **Subject | **:** | Forensic | **Discuss | **:** | 3 | | ** | | Chemistry | ion | | | | | | and | and | | | | | | Toxicolog | Assessmen | | | | | | y | t | | | | | | | No.** | | | +===========+===========+===========+===========+===========+===========+ | **Class | **:** | BSC 3A, | | | | | Schedule* | | 3B and 3C | | | | | * | | | | | | +-----------+-----------+-----------+-----------+-----------+-----------+ | | | | | | | +-----------+-----------+-----------+-----------+-----------+-----------+ | **Topics* | **:** | - Gunsh | | | | | * | | ot | | | | | | | Resid | | | | | | | ue | | | | +-----------+-----------+-----------+-----------+-----------+-----------+ | | | | | | | +-----------+-----------+-----------+-----------+-----------+-----------+ | **Objecti | **:** | - At | | | | | ves** | | the | | | | | | | end | | | | | | | of | | | | | | | this | | | | | | | weekl | | | | | | | y | | | | | | | modul | | | | | | | e, | | | | | | | you | | | | | | | must | | | | | | | have: | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Diffe | | | | | | | rentiate | | | | | | | the | | | | | | | terms | | | | | | | relat | | | | | | | ed | | | | | | | to | | | | | | | gunpo | | | | | | | wder | | | | | | | exami | | | | | | | nation. | | | | | | | | | | | | | | - Analy | | | | | | | zed | | | | | | | the | | | | | | | impor | | | | | | | tance | | | | | | | of | | | | | | | gunsh | | | | | | | ot | | | | | | | resid | | | | | | | ue | | | | | | | in | | | | | | | gunpo | | | | | | | wder | | | | | | | exami | | | | | | | nation | | | | +-----------+-----------+-----------+-----------+-----------+-----------+ | | | | | | | +-----------+-----------+-----------+-----------+-----------+-----------+ **I. ACTIVITIES** Direction: Watch a short clip video about the gunshot residue. Click the link attached below. After watching, write a reaction paper in the space provided below. Short clip video link: -- -- **II. ABSTRACTION**  **GUNSHOT RESIDUE** Basically, gunshot residue come from the powder component of bullet, elements from cartridge cases and gun barrel where the bullet passes. When these components are burned, certain products of combustion are formed which includes partially burned and unburned particles. These particles are deposited on the target as definite pattern depending upon the distance between the muzzle of the gun and the target at the time of discharge. Upon discharge of firearm, gunpowder residues (nitrates) may be deposited on a person at close proximity, so the interpretations as to who discharged the firearm should be made with caution. Hand or body part close to the fired weapon may have gunpowder residues consistent with having discharged the weapon. However, absence of gunpowder residues on the person's hands or body parts does not mean that he/she did not discharge a firearm. Gunpowder residue may be found on the skin or clothing of a person who discharged the gun, on the entrance bullet hole of garment or wound of the victim or on other target materials at the scene. **Components of gunshot residue** 1. Primer or lead residue 2. Gunpowder residue 3. Elemental component from cartridge cases residues **Composition of Primer** Primer elements may be easier to detect in residues because they do not get as hot as that of powder. 1. Major primer elemental composition: lead (Pb), barium (Ba), or Antimony (Sb). 2. Trace element: aluminum (Al), sulfur (S), tin (Sn), calcium (Ca), potassium (K), chlorine (Cl) or silicon (Si). 3. In organic compound: mercury fulminates (present in most ammunition manufactured in Eastern Europe and used in Middle East). **Composition of gunpowder** 1. Contains up to 23 organic compounds (FBI Study) 2. Nitrocellulose is virtually always present along with nitrate and nitrogen containing compound such as Diphenylamine or DPA (stabilizer in the powder). **Types of gunpowder** 1. Single based -- when the basic ingredient is nitrocellulose 2. Double based -- nitrocellulose + 1 to 40% nitroglycerine 3. Triple based -- nitrocellulose + nitroglycerine + nitro guanidine These can be differentiated using a mass spectrophotometer. **Composition of cartridge case, bullet coating and metal jacket** 1. Cartridge and primer cases; BRASS (7:3 COPPER-ZINC) 2. Bullet cores: lead, lead, antimony and few iron alloy 3. Bullet jackets: brass (9:1 copper-zinc), some are iron or aluminum alloy. Some contain nickel. **GUNSHOT RESIDUE EXAMINATIONS** **Purpose** Gunshot residue examinations are performed to the help of investigators in determining whether a person has discharged a firearm or not; and the possible gunshot range or the distance of the shooter to the victim. Both hands of the suspect as well as those of the victim, the firearms and clothing of the victim must be examined to determine the presence of gunpowder nitrates. **Types of Powder used in the ammunition of small firearms** **There are two types of powder used in the ammunition of small firearms. These are:** 1. **Black Powder** -- this consists of a mixture of carbon (Charcoal), sulfur and potassium nitrate. This mixture is used as an igniter in smokeless gun propellant. It consists of a mixture of 15% charcoal, 10% Sulfur and 75% Potassium nitrates. Aluminum is added to enhance the burning property. When this powder is burned, combustion reaction takes place: **2KNO3 + 2o2 + S + C CO2 + SO2 + K202 = 2NO2** 2. **Smokeless Powder** -- this mixture consists of Cellulose or glycerol nitrate combined with some stabilizers (nitrobenzene or graphite nitrates, dichromate and oxalates). When this powder explodes, the chemical reaction takes place. Cellulose nitrate: C12H1404 (NO3)6 + 6H20+3N2+4CO2+8CO+H2 **Primers** To explode a low explosive, flame is required. In guns, the flame is applied by means of a primer. Primer produces flame on percussion. A typical primer consists of a case containing an initiating explosive such as mercury fulminate, an oxidizing agent such as potassium chlorate or barium nitrate and a fuel such as antimony sulfide. This component is the basis for examination of gunshot residue particularly primer residues for distance determination. **DETETCTION OF GUNSHOT RESIDUE** The following are common methods used by most crime laboratories to detect gunshot residue: 1. Paraffin test 2. Lead residue (detection limit: up to 30 feet and always present on the opposite sides of the penetrated target). Reported from intermediate glass target present (Messler and Armstrong, 1978). 3. Gunpowder residue examination (detection limit: highly variable up to 20 cm and up to 21 inches is common). 4. Other examinations The last two methods are classical. Color development or modern methods such as Neutron Activation Analysis (NAA), atomic absorption spectrophotometry (AAS), Scanning Electron microscopy with energy dispersive analysis (SEM-EDA) and inductively coupled plasma with mass spectrophotometry (ICP-MS) are used. **History of Paraffin test/ dermal nitrate or Diphenylamine test** Paraffin test was originated from Cuba when Dr. Gonzalo Iturrios first used paraffin for collecting gunpowder residues from discharged firearm. In 1933, Teodor Gonzales of Criminal Identification Laboratory Mexico City introduced the test in the United States. In Mexico City introduced the test in the United States. In this test, the hands were coated with a layer of melted paraffin. After cooling, the casts were removed and treated with Diphenylamine (5% DPA in 60% sulfuric). **Methods of Examination** **Paraffin Test** To determine whether a person has discharged a firearm, the Paraffin-Diphenylamine test is used. The basis of this test is the presence of nitrates in the gunpowder residue. When a warm melted paraffin wax is applied on the hands of the alleged shooter, it will cause the pores of the skin to open and exude the particles of gunpowder residue. These particles of gunpowder residue are being extracted by the paraffin cast (with the use of melted paraffin was) and will appear as blue specks, when diphenylamine reagent (DPA for brevity) is added on the cast. It must be noted that the specks are generally located on the area of the thumb and forefingers. **Note:** The blue color that appears indicates the reaction of nitrates with diphenylamine reagent. Thus, nitrate from other sources like fertilizers will give the same reaction. Other substances similar to nitrate known as oxidizers will also react with the reagent in the same way. However, it must also be noted that the blue specks have the characteristics of "tailing". **What is the Principle behind the Paraffin test?** While the burned and partially burned particles (gunpowder residue) is deposited on the target and in the barrel of the gun, some of these burned and partially burned particles may escape around the breech of the gun and some may be embedded on the exposed surface of the hand/s of the person discharging the firearm. Thus, the presence of these residues can be detected by way of paraffin examination. As a rule, in the paraffin examination, the Forensic Chemist/Chemical officer should personally conduct the paraffin casting on the alleged shooter. However, a competent laboratory technician under the supervision of the examiner-on-case may also perform the paraffin casting. But it is the Forensic Chemist/Chemical officer who should examine the paraffin casts taken from both hands of the alleged shooter to determine the presence of gunpowder nitrates. Paraffin casting of the alleged shooter shall only be done with seventy-two (72) hours from the time of the alleged shooting incident. No person shall be subjected to paraffin casting after the lapse of the specified period. Embalmed cadaver who allegedly discharged a firearm shall no longer be subjected to paraffin examination because of the impossibility of extracting the gunpowder nitrates from the former's hands. **Taking of Paraffin Casts** **Materials and Apparatus:** **Paraffin wax (M.P. 38-40 C)** - Absorbent cotton - Bond paper - Burner - Beaker or casserole - Tong **Procedure** a. Heat the paraffin wax in a container until it melts. Allow cooling for a few minutes so that it will not burn the skin. b. Let the subject wash his hands with water without using any soap or detergent. Wipe the hands of the subject with clean absorbent cotton. c. Let the subject place his hands on a clean sheet of bond paper with the palms facing downward and the fingers closed together. Using a spoon or tong with cotton, pour the melted paraffin wax on the hands of the subject from the thumb and index fingers and the dorsal portion to the little finger side of the hands. d. Cover the hands and fingers thoroughly with paraffin wax and place a thin layer of absorbent cotton to reinforce the wax. e. Pour another layer of the wax until the absorbent cotton has totally absorbed the wax. f. Allow the wax to cool and solidify before feeling them off. g. When cool, direct the subject to move his fingers first and slowly moving his hands out from the casts. h. Place on the bond paper the case number, name of the subject, time and date, technician who took the cast, witnesses and label the right and left hand. i. Place another bond paper on top of the paraffin casts and staple together. j. Place the paraffin casts inside an envelope or a box for proper preservation. **Note**: It must be noted that upon casting, the melted paraffin wax penetrates the minute crevices of the skin thus, the burned and partially burned gunpowder nitrates which are embedded on the hands of the shooter are extracted. Upon application of Diphenylamine (DPA) reagent on the paraffin casts, the appearance of "tailing deep blue specks" indicates the presence of gunpowder nitrates. **Paraffin Wax** Paraffin wax is a white, translucent, tasteless, odorless solid consisting of a mixture of solid hydrocarbons of high molecular weight. It is insoluble in water and acids and soluble in benzene, ligroin, warm alcohol, chloroform, turpentine, carbon disulfide and olive oil. Combustible, auto ignition temperature 473 F (245°C) The melted paraffin wax penetrates the minute crevices of the skin upon application, thus, adhering if there are particles present. When the casts are peeled, the burned and partially burned particles are extracted. A person firing a gun will likely have the particles located above the thumb and forefingers since these are the surfaces exposed to the gun. **What should be noted in the interpretation of results:** **Time of reaction** - Number and characteristics of blue and minute specks - The location and character of the blue specks - Distribution and location **Different names of this test:** - Lunge's test - Diphenylamine test - Dermal nitrate test Gonzales test -- named after the one who improved the test **Question**: Is there any means of removing these nitrates from the hands? How long will they stay in the pores? Answer: None. Ordinary washing will not remove the nitrates from the pores of the skin. Usually, gunpowder nitrates that are embedded on the skin stay for 72 hours. That is why paraffin casting should be conducted within the specified period. **Substances giving false positive result:** 1. Fertilizers 2. Explosives 3. Tobacco 4. Urine 5. Certain cosmetics 6. Food samples 7. Cigarette **Question: Will these substances not give positive result for paraffin test?** Answer: If the hands of the subject person are contaminated with nitrates other than from gunpowder, one will expect to find smudges or just a smear of blue color or a conglomeration of blue specks. But nitrates from gunpowder appear as blue speck with tailings, because these particles were embedded into the hands with force. **Question: Is paraffin test result a conclusive evidence? Why?** Answer: No. it is just a corroborative evidence which intends to support the testimony of eyewitness/es, these are instances wherein a person who actually discharged a firearm would still give a negative result to the paraffin test because of several factors. **Question: What are these factors?** Answer: 1. Types of caliber of ammunition 2\. Use of gloves 3\. Length of the barrel 4\. Age of the gun / efficiency of mechanism 5\. Direction of firing 6\. Wind direction 7\. Humidity/percentage moisture in air 8\. When 72 hours had already lapsed (3 days) **Types of caliber ammunition**. A hand discharging a revolver is more likely to give a positive result for gunpowder nitrates compared to that of a hand discharging a pistol. In an automatic pistol, the chamber is an integral part of the barrel, whereas in the revolver, the chamber is located in the cylinder and separated from the barrel with airspace. Thus, leakage of powder in a revolver is more likely to occur. **False Positive Result** 1. Contamination or transfer of gunshot residue (GSR) to the body by mishandling or when the body is heavily contaminated by GSR from previous shooting. 2. Washing of hands where samples are collected. 3. Type of ammunition such as rifle and shot gun. **Length of the barrel**. A weapon of 2-inch barrel will deposit residue over a larger area than a weapon of 5-inch barrel (even if they are discharged from the same distance with the same type of ammunition). In a longer barrel, the hand is father away from the muzzle end of the gun. It takes a bullet to travel in more time, thus using up/burning up more, if not all, of the nitrates. In a short barrel, the bullet travels through the barrel in less time leaving behind a greater amount of unburned particles. **Age of the gun/efficiency of mechanism.** Complete combustion or the conversion of all nitrates into its end product (CO,CO,N,O,-OH) is more likely to occur in a new weapon compared to an old one. Besides, leakage of gunpowder is more likely to happen in the old weapon where the breech mechanism is no longer tingly fitted. **Direction of firing.** More powder residues will be obtained when the gun is discharged pointing upward than downward. Gunpowder residues have weight and will naturally fall down because of gravity. **Wind direction and velocity.** In high velocity (strong wind), the power residues will be blown in the direction of the wind. One is more likely to be positive for gunpowder nitrates if there is no wind, or the wind direction is towards the shooter. **Humidity/percentage moisture in air.** Humidity lessens the extent of combustion yielding more gunpowder nitrates. **False Positive reaction** -- smear blue color or conglomeration of blue specks on both dorsal and palm aspects of the hand. Failure to find traces of nitrate on the hand of the person does not prove that he did not fire a gun. But it is submitted that the paraffin test has some value due to the psychological effect on the persons whose hands were found positive. Also, the finding of actual traces of gunpowder nitrates on the hand/s of the person does not conclusively determine or establish that he has discharge a gun. It is possible that the GPR particle may have been blown on the hand directly from the barrel of the gun being discharged by another person. **Gunpowder Residue Test on Firearms** The diphenylamine reagent is also applied to cotton swabbing of the barrel and chambers of the gun to determine if the firearm was discharged. A deep blue color resulting from the reaction of nitrates with the reagent indicates presence of gunpowder residue. **Established Forensic Rules:** a. The Forensic Chemist on case shall conduct the gunpowder residue examination (GPR) without delay. b. After the examination is done, the firearm shall be returned to the representative of the requesting unit if the request is solely for gunpowder residue (GPR) examination, or submitted to the FAID if ballistic examination is required. **Gunshot Range Determination (Also known gunshot distance determination)** When a firearm is discharged, gunpowder residue may also be deposited on the clothing of the victim. The size and density of the pattern of the gunpowder residue found on clothing are the main factors considered in determining the approximate distance of the shooter to the victim. As the distance to the victim increases, the size of pattern expands while density decreases and vice-versa. **Distance determination** -- the method of determining the distance between the firearm and the target. This is usually based on the distance of the powder patterns or the spread of the shot pattern. **Importance of Distance Determination** 1. In connection to self-defense pleas 2. In the distinction between murder and suicide. It is possible to state with certainty the distance of the gun from the target by means of the patterns and residues left on the target. Not only the type of gun, but also the condition and type of ammunition that will affect this pattern. 1. Entrance and exit holes 2. Powder residue pattern (burning, singeing, smudging, tattooing -- a black coarsely peppered pattern) **Entrance and Exit holes:** Entrance hole contains gunpowder residue (bullet wipe residue) and it is slightly burned. The diameter of entrance hole is smaller than the exit hole. The exit hole is frayed outward while entrance hole is inward. **Other Entrance hole characteristics:** a. Angled bullet hole has elongated hle. b. Contact fires have uneven margins but all entrance holes typically have even margins. c. Grazing bullet hole (several small holes created from a folded garment). **Classification of Gunshot Distance** - Burning (direct) - Singeing (1 to 2 inches) - Smudging (2 to 8 inches) - Tattooing (8 to 18 inches) **The distance of the muzzle of the gun to the target is classified into three (3):** 1. Direct contact 2. 2 inches to 36 inches away 3. 36 inches away or more **Tests for Gunshot Residue (GSR)** - Nitrite and - Lead residue chemical examination **Characteristics of Gunshot wounds** A. **Direct/contact wounds** The principal damage is more visible due to the flame and the muzzle blast than to the penetration of bullet. The following observations may be noted: 1. Gaping hole where fabric is badly thorn 2. Blackened area surrounding the bullet hole 3. The presence of partially burned powder residues around the entrance hole. B. **Wounds inflicted at a distance from 2-36 inches** If the gun is discharged closely to the body of the victim, two (2) types of discoloration will be observed around the hole of the entrance namely: (1) smudging and (2) powder tattooing (black coarsely peppered pattern). **Smudging** -- is produced when the gun is held from about 2 inches to the maximum of 8 inches. The smoke and soot from the burned pores are deposited around the hole of the entrance producing a dirty appearance. The size of the smudge depends upon the following: a. **Length of the barrel** -- a weapon of 2-inch barrel will deposit residue over a larger area than a weapon of --inch barrel (even if they are fired from the distance with the same type of ammunition). In a longer barrel, the hand is farther away from the muzzle end of the gun. It takes a bullet to travel in more times, thus, using up/burning up more, if not all, of the nitrates. In short barrel, the bullet travels through the barrel in less time leaving behind a greater amount of unburned particles. b. **Age of the gun/efficiency of mechanism** -- complete combustion or the conversion of all nitrates into its end product is more likely to occur in a new weapon compared to an old one. Besides, leakage of gunpowder is more likely to happen in the old weapon where the breech mechanism is no longer tightly fitted. c. **Direction of Firing** -- more gunpowder residues will be obtained when the gun is fired upward than downward. Gunpowder residues have weight and will naturally fall down because of gravity. d. **Wind Direction and Velocity** -- in high velocity (strong wind), the powder residues will be blown in the direction of the wind. One is more likely to be positive for gunpowder nitrates if there is no wind, or the direction is away from the body. e. **Humidity/percentage moisture in air** -- Humidity lessens the extent of combustion yielding more gunpowder nitrates. - Caliber - Powder charge - Distance of firing C. **Wounds inflicted at a Distance of more than 36 inches**: - Powder tattooing is seldom present. - Nitrates found will not be sufficient for GSR **FIREARM EXAMINATION** Methods used to determine the probable time the firearms has been discharged: a. **Lucas test** A characteristic smell that decreases in intensity with lapse of time is present immediately after firing but even after several weeks some slight smell remains. b. **Odor (Hydrogen Sulfide)** This is another product resulting from combustion of gunpowder which is present in the gaseous state. This compound can be detected by means of lead acetate paper test. If the breech of the gun is kept closed, this persists between 2-3 hours. ***Sulfide*** -- the greater part disappears in about 4-5 hours but frequently a trace remains for a longer time, the longest period being 10 hours. c. **Odor of the barrel (rusting)** As a rule, no rust can be detected inside the barrel of a firearm if such firearm has been discharged. But if the firearm has been discharged, iron salts are formed and can be detected inside the barrel. These iron salts are soon oxidized resulting in the formation of rust. The formation of rust is affected by the humidity of the air so that in the interpretation of the result, this factor must always be considered. d. **Presence of Nitrates (by cotton swabbing method)** Nitrates diminish after a lapse of time. Nitrates can be detected by swabbing a portion of residue in a barrel and mixing the residue with Diphenylamine solution (DPA). e. **Dermal Nitrate test** The test is designed to determine the presence of gunpowder nitrates on the hands of the alleged shooter. **Distance from which the gun has been discharged** **Significance**: a. In connection with self-defense. b. In the distinction between murder and suicide. It can be stated with certainty the distance of the gun from the target by way of patterns of residues left on the victim. **Scorching or Singeing** If a firearm was discharged very close to the target as in a case of alleged suicide and sometimes in murder, burns or scorches may result. This resulting reaction is caused by flame that emerges from the muzzle and travels only a short distance from it. This distance will vary with the length of the barrel, the size of the powder charge and the degree to which the bullet fill the barrel. The presence of scorch is a proof that the firearm was discharged a few inches away from the target. Scorching is very rare if the victim was shot 3 inches or more away from the muzzle. **Other Methods of Examination** The following are the sophisticated instruments used to determine the gunshot range residue (GSR): **AAS** -- Atomic Absorption Spectrophotometer **NAA** -- Neutron Activation Analysis **SEM-EDX** -- Scanning Electron Microscope with Energy Dispersive X-ray Analysis **ICP-MS** -- Inductively Couled Plasma with Mass Spectrophotometry **COLLECTION, PRESERVATION AND TRANSIT OF SPECIMEN** Important points to remember in the collection, preservation and transit of specimen: a. Clothing removed from the victim should be cautiously and carefully handled to prevent powder residues from becoming dislodged. b. Do not wad the specimen or pack it loosely for shipment. c. Secure the area to be tested between two layers of heavy cardboard fastened together tightly to prevent the specimen from becoming postlude about in transit. d. Each specimen should be wrapped tightly and marked. e. Clothing heavily smeared with blood should be fried thoroughly before packing. f. Gun recovered from the scene of the crime and ammunition available should be preserved. g. Person suspected to have discharged a firearm should be subjected to a paraffin test. (Cover his hands with paper bags to avoid contamination). Examination must be performed immediately and in no case should it be postponed 72 hours after the shooting. **III. ASSESSMENT** A. **Let's Make a Venn Diagram!** 1. Black Powder and Smokeless Powder 2. Entrance Hole and Exit Hole 3. Singeing and Smudging B. **Let's Make an Essay!** C. **Let's Have a Quiz!** 1. It is a white, translucent, tasteless, odorless solid consisting of a mixture of solid hydrocarbons of high molecular weight. A. Floor Wax B. Paraffin Wax C. Paraffin Glue D. Explosives 2. It is a test which determines the presence of nitrates in the gunpowder residue left on the hand of the perpetrator. A. Paraffin Test B. Lunge's Test C. Dermal nitrate Test D. All of the Above 3. It comes from the powder component of bullet, elements from cartridge cases and gun barrel where the bullet passes. A. Fertilizer B. Gunshot residue C. Smokeless powder D. Hydrogen Sulfide 4. It is a type of powder which consists of a mixture carbon, sulfur and potassium nitrates. This mixture is used as an igniter in smokeless gun propellant. A. Black powder B. Blue powder C. Smokeless powder D. Sulfur powder 5. Where does the Paraffin Test originated? A. United States B. Mexico City C. Cuba D. Cebu 6. Which of the following is not a name of paraffin test? A. Lunge's test B. Diphenylamine test C. Dermal sulfur test D. Gonzales test 7. Which of the following substance that does not give a false positive result? A. Explosives B. Cigarette C. Tobacco D. Gunpowder 8. It is produces when the gun is held from about 2 inches to the maximum of 8 inches. The smoke and soot from the burned pores are deposited around the hole of the entrance producing a dirty appearance. A. Singeing B. Tattooing C. Smudging D. Burning 9. It is a type of examination using a microscope which is commonly used in comparison of an empty shell containing characteristic marks from grooves of the gun barrel and firing pin of specific firearm used. A. Lucas test B. Bullet comparison C. Dermal nitrate test D. Neutron Activation Analysis 10. This test is designed to determine the presence of gunpowder nitrates on the hands of the alleged shooter. A. Lucas test B. Bullet comparison C. Dermal nitrate test D. Neutron Activation Analysis