2Forensic analysis is vital to solve a crime that uses a gun. FirearmsForensic analysis is vital to solve a crime that uses a gun.The vast majority ofU.S. homicides involveguns. And they are morepowerful than ever.Lansing State Journal, July 2007In 2004, there were 12,000 homicides in the United States.
3Types of Firearms Handguns (pistols) Rifles Shotguns Air or BB guns RevolverSemiautomaticRiflesShotgunsAir or BB guns
4Cartridge case Primer Propellant Projectile AmmunitionComponents:Cartridge casePrimerPropellantProjectile
5Made of lead, sometimes jacketed with brass, copper, or steel BulletsMade of lead, sometimes jacketed with brass, copper, or steelBullet size—diameter (caliber or gauge)Shapes
6RiflingThe grooved spirals inside the barrel of a gun that produce lands and grooves on a bulletLands and grooves are class characteristics.
7Scratches on a fired bullet, like a barcode, StriaeScratches on a fired bullet, like a barcode,that can serve as individual evidence, matching bullets or bullet to a firearm
8Usually brass or nickel-clad brass Cartridge CaseUsually brass or nickel-clad brassHead stampsRimfire and centerfire cartridgesClass evidence
9Cartridge Case, continued Individual characteristicsFiring pin marksExtractor marksBreech marks
12Firearms Evidence Individual: Class: Striae Firing pin marks Breech marksExtractor marksEjector marksChamber marksClass:Bullet typeBullet caliberBullet weightLands and groovesRiflingCartridge caseHead stamp
13Gunshot Residue (GSR) When a weapon is fired: Primer and propellant particles blow back toward the shooter.Combustion products (mostly NO2-), unburned propellant, andparticles of lead follow the bullet, spreading out with distance.
14Distance to TargetThe Greiss test converts nitrites to an orange-red color.Sodium rhodizonate reacts with traces of lead to makepurple spots.
15Tools often used in burglaries may leave a mark. ToolmarksTools often used in burglaries may leave a mark.Class characteristics: type, size, shapeIndividual characteristics: features from wear and damage
16Lab Activity: Matching Toolmarks ??Photography and casting are important to match tool with mark.
18Impressions, continued ShoeprintsCaptured by oblique-angle photography or chemical enhancement; also by casting in soil, or lifting.
19Impressions, continued Treated much the same as shoeprintsTire TreadsClass characteristics involve design, size, type, and model.Wear and damage cause defects that can lead to individualization.
20Impressions, continued Tire TreadsTreadMate is a database containing data on more than 5,000 vehicle tires and tread patterns.
21Impressions, continued Serial NumbersRestoration of serial numbersItems of value may have ID numbers stamped into them.Grinding is usually used to obliterate identification numbers.To restore ID numbers on metal, an acid etching solution is employed.HCl-CuCl2
22Forensic Odontology Jason Linville firstname.lastname@example.org University of Alabama at BirminghamUsed with permission
23History Body Identification Bite Mark Analysis Forensic OdontologyHistoryBody IdentificationRoman Emperor Claudius - wife wanted decapitated head of mistressPaul Revere – dentures of soldierBite Mark AnalysisKing William - bite in wax
24Education: Forensic Odontologists are dentists first. Forensic OdontologyEducation:Forensic Odontologists are dentists first.D.D.S. or D.D.M. degreeCertification available from the American Board of Forensic Odontology
25Anatomy of Oral Cavity: Forensic Odontology > Body IdentificationAnatomy of Oral Cavity:Maxilla – upper jawMandible – lower jaw
26Anatomy of Oral Cavity Primary dentition Baby teeth or milk teeth Forensic Odontology > Body IdentificationAnatomy of Oral CavityPrimary dentitionBaby teeth or milk teeth20 teeth
27Anatomy of Oral Cavity Permanent dentition Start at 6-8 years old Forensic Odontology > Body IdentificationAnatomy of Oral CavityPermanent dentitionStart at 6-8 years old32 teeth
28Anatomy of Tooth Crown Enamel Pulp Root Cementum Forensic Odontology > Body IdentificationAnatomy of ToothCrownEnamelPulpContains DNARootCementum
29Forensic Odontology > Body Identification A body is identified by comparing teeth and bone structures of the body to the dental records of the suspected individual.
30A body is identified in 3 steps: Forensic Odontology > Body IdentificationA body is identified in 3 steps:1. Postmortem examination of the body2. Locating the antemortem dental records3. Comparing the body to the dental records
31Postmortem Examination: Forensic Odontology > Body IdentificationPostmortem Examination:May examination teeth while in the body (if body needed for funeral)orMay remove jaw (using bone saw) and remove soft tissue using hydrogen peroxide.
32Postmortem Examination Forensic Odontology > Body IdentificationPostmortem ExaminationEach tooth or socket is examined individually and the following is recorded:1. Presence/absence of tooth2. Socket present or healedHealed socket = past removalPresent socket = recent removal3. Erupted vs. Unerupted4. Filling or Crown Material
33Postmortem Examination Forensic Odontology > Body IdentificationPostmortem ExaminationEach tooth or socket is examined individually and the following is recorded:Also record any diseases and the general anatomy.
34Postmortem Examination Forensic Odontology > Body IdentificationPostmortem ExaminationAfter examination of teeth, they should be photographed and X-rays should be taken.
35Forensic Odontology > Body Identification Antemortem RecordsIf body is known, dental records can usually be recovered from his or her dentist.If body is unknown, the examination results are submitted to a missing person registry.
36Comparison Consistent Different with explainable differences Forensic Odontology > Body IdentificationComparisonPostmortem exam compared to antemortem records.A statement is made about each tooth:ConsistentDifferent with explainable differencesDifferent with no explanation
37Identification in Mass Disasters: Forensic Odontology > Body IdentificationIdentification in Mass Disasters:Split into 4 teams. Run by Chief Forensic Dentist.1. Recovery at disaster scene.2. Postmortem exams at morgue.3. Collect antemortem dental records.4. Comparisons with computer software.
38Characteristics of Bite Marks: Forensic Odontology > Bite Mark IdentificationCharacteristics of Bite Marks:Usually shape of two half moons (upper/lower)Usually composed of 6 upper / 6 lower teeth
39Characteristics of Bite Marks: Forensic Odontology > Bite Mark IdentificationCharacteristics of Bite Marks:Antemortem (diffuse bruise)Perimortem (defined bruise)Postmortem (no bruise)Only persists 8 hours on living person
40Collection of Bite Marks Forensic Odontology > Bite Mark IdentificationCollection of Bite Marks1. Identify as potential bite mark2. Collect 3 swabsABO blood test, amylase detectionDNA analysisMicroorganism analysis3. Photograph bite mark4. Make an impression of bite mark
41Comparison of Bite Marks: Forensic Odontology > Bite Mark IdentificationComparison of Bite Marks:Photographic overlay of suspect’s teeth and bite mark.Compare mold of suspect’s teeth to bite mark or impression of bite mark.
42Impressions, continued Bite MarksResult from assault or sexual attack, common in domestic violenceIndividual evidence, if enough impressionsBite marks were the prime evidence in the conviction of serial killer Ted Bundy.