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Chapter 21 – Firearms and Tool Marks FRSC 7104 Criminalistics I Professor Bensley.

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Presentation on theme: "Chapter 21 – Firearms and Tool Marks FRSC 7104 Criminalistics I Professor Bensley."— Presentation transcript:

1 Chapter 21 – Firearms and Tool Marks FRSC 7104 Criminalistics I Professor Bensley

2 FRSC 7104 – Chapter 21 Objectives After studying this chapter, the student should be able to: Recognize the various types of firearms and their basic components Recognize the various types of ammunition and their uses Understand how firearms evidence is collected and analyzed Describe the basic details of tool mark comparisons and firing distance determinations

3 FRSC 7104 – Chapter 21 Outline I.Introduction FBI Uniform Crime Reports (2011) Murder Victims by Weapon, 2007– Total14,91614,22413,75213,16412,664 Total firearms:10,1299,5289,1998,8748,583 (68%)(67%) (68%) Handguns7,3986,8006,5016,1156,220 Rifles Shotguns Other guns Firearms, type not stated1,7051,8251,8281,9331,587 Knives or cutting instruments1,8171,8881,8361,7321,694 Blunt objects (clubs, hammers, etc.) Personal weapons (hands, fists, feet, etc.) Poison Explosives Fire Narcotics Drowning Strangulation Asphyxiation Other weapons or weapons not stated1, Pushed is included in personal weapons.

4 FRSC 7104 – Chapter 21 Outline II.Firearm Examinations A.Types of Firearms 1.Handguns a.Revolvers i.Single action ii.Double action

5 FRSC 7104 – Chapter 21 Outline b.Semi-automatic pistols

6 FRSC 7104 – Chapter 21 Outline 2.Rifles (Shoulder arms)

7 FRSC 7104 – Chapter 21 Outline a.Semi-automatic b.Automatic c.Machine Guns d.Submachine Guns

8 Top -.50 caliber M2 machine gun Bottom - Heckler & Koch MP5 submachine gun

9 FRSC 7104 – Chapter 21 Outline 3.Shotguns

10 FRSC 7104 – Chapter 21 Outline B.Firearm Construction

11 FRSC 7104 – Chapter 21 Outline 1.Rifling a.Lands and Grooves

12 FRSC 7104 – Chapter 21 Outline b.Broach rifling

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15 FRSC 7104 – Chapter 21 Outline c.Button Rifling

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17 FRSC 7104 – Chapter 21 Outline d.Hammer forged rifling e.Electrochemical Rifling

18 Bullet Impressions Left - A bullet fired from a conventional 6/right rifled barrel Right – 40 Caliber bullet with polygonal rifling impressions like those seen on the 40 caliber bullet

19 FRSC 7104 – Chapter 21 Outline 2.Caliber

20 Caliber Left to Right:.50 caliber down to.22 caliber

21 FRSC 7104 – Chapter 21 Outline 3.Gauge

22 FRSC 7104 – Chapter 21 Outline C.Firearm Ammunition 1.Bullets 32 S&W LONG caliber plain lead bullet 9mm LUGER caliber FEDERAL "Hydra-shok" bullet 7.62x39mm caliber armor piercing bullets

23 FRSC 7104 – Chapter 21 Outline 2.Propellants 3.Primers 4.Cartridge Cases 5.Shot shells Video of Firing Action in a Firearm

24 Plain Lead Bullet

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28 FRSC 7104 – Chapter 21 Outline D.Forensic Examinations of Firearms 1.Class vs. Individual Characteristics Land Impressions: Left AUTO caliber FMJ bullets fired from a EAA Corp. pistol Right - 9mm LUGER caliber FMJ bullets fired from a BROWNING pistol.

29 General Rifling Characteristics Search CARTRIDGEMANUFACTURERTWISTL&GLANDGROOVE 9MM LUGERAA ARMS INCR MM LUGERASTRAR MM LUGERBERETTAR MM LUGERHI-POINT FIREARMSR MM LUGERINTERDYNAMICR MM LUGERLLAMAR MM LUGERMAUSERR MM LUGERSMITH & WESSONR MM LUGERSTARR MM LUGERSWD INCR mm LUGER bullet, fired from a 6/right rifled barrel, with a land width of.055mm and a groove width of.125mm. Firearm examiners will usually search with a plus or minus tolerance and the results of the search would look something like the data contained in the above table.

30 FRSC 7104 – Chapter 21 Outline 2.Bullet Identification

31 Bullet Fragments Image below shows the bullet fragments from left compared to a known standard bullet. Standard is on the left side of the comparison below.

32 FRSC 7104 – Chapter 21 Outline 3.Cartridge Case Identification

33 FRSC 7104 – Chapter 21 Outline a.Striated Action Marks i.Chamber Marks

34 FRSC 7104 – Chapter 21 Outline ii.Shear Marks

35 FRSC 7104 – Chapter 21 Outline iii.Firing Pin Drag Marks iv.Extractor Marks v.Ejector Marks b.Impressed Action Marks i.Firing Pin Impressions

36 FRSC 7104 – Chapter 21 Outline ii.Breech Marks Breech face of 12 gauge shotgun and photomicrograph of cartridge case fired from the same weapon. iii.Ejector Marks E.NIBIN

37 Fun Movies

38 FRSC 7104 – Chapter 21 Outline III.Gunshot (Gunpowder) Residue A.What causes gunpowder residue?

39 FRSC 7104 – Chapter 21 Outline B.Distance Estimations (Determinations) 1.Ranges of fire a.Contact b.Near-contact c.Intermediate d.Distant

40 FRSC 7104 – Chapter 21 Outline C.Powder Residue Detection Methods 1.Visual 2.Chemical a.Griess Test (Modified Griess Test)

41 FRSC 7104 – Chapter 21 Outline b.Sodium Rhodizonate 1. Untreated 12 inches 2. Greiss Test 12 inches 3. Greiss followed by Sodium Rhodizonate

42 FRSC 7104 – Chapter 21 Outline D.Gunshot Residue on Hands E.GSR Analysis Techniques

43 FRSC 7104 – Chapter 21 Outline F.Bullet Holes 1.Entrance Wounds 2.Exit Wounds

44 FRSC 7104 – Chapter 21 Outline IV.Toolmark Examinations A.Introduction Forged Key Toolmarks Lock Picking Toolmarks

45 FRSC 7104 – Chapter 21 Outline B.Types of Toolmarks 1.Indentations 2.Striations

46 FRSC 7104 – Chapter 21 Outline C.Class vs. Individual Characteristics in Toolmarks D.Unusual Toolmark Types

47 FRSC 7104 – Chapter 21 Outline E.Collecting and Processing Toolmark Evidence 1.Photography 2.Processing at Crime Scene

48 FRSC 7104 – Chapter 21 Outline 3.Trace Evidence 4.Processing in the lab a.Cast vs. Mold 5.Lab Examinations


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