2 Forensic Engineering Concerned with: Failure analysisAccident reconstructionCause and origin of fires or explosionsAnswer questions such as how did an accident occur or what structural failure occurred
3 Forensic PathologyInvolves the investigation of sudden, unnatural, unexplained, or violent deaths.Typically these are the medical examiners or coronersAnswer questions: who is the victim, what injuries are present, when did the injuries occur, why and how were the injuries produced, and what is the cause of death
4 Criminalist (CSI)Analyzes, compares, identifies, & interprets physical evidence at crime scenes.Criminalists examine and identify physical evidence to reconstruct a crime scene. Physical evidence can be a weapon, a piece of clothing, a bloodstain, drugs, or even a vapor in the air. Criminalists use physical evidence to provide a connection between the suspect and the victim. Such connections are acquired by the transfer of hair or clothing fibers from a suspect to the victim. Other connecting links are fingerprints, bullets, or shoe impressions. Physical evidence is collected from a crime scene that includes the victim's body and the surrounding area of the crime.
5 Forensic Anthropology Identification and examination of human skeletal remainsTrying to determine origin, sex, approximate age, race and skeletal injuryMay create facial reconstructionIdentify victims of mass disaster such as plane crash
6 Forensic Toxicologist Analyses alcohol, drugs, & poisons in body fluids for the benefit of the courts.Forensic toxicology is essentially a specialty area of analytical chemistry which specifically looks at body fluids for presence of drugs, poisons, and/or alcohol.
7 Manner of DeathNatural:HomicideSuicideAccidentalUndetermined
8 Cause of Death Asphyxiation Exsanguination Blunt force trauma StrangulationDrowningFire victimExsanguinationMajor blood lossBlunt force traumaSharp force traumaChemical trauma
9 Estimated Time of Death AutopsyRigor Mortis: the stiffening of body parts in the position they are in when death occurs.Lividity: medical condition that occurs after death and results in the settling of blood in areas of the body closest to the groundBody Temp: postmortem changes that cause a body to lose heat o C/hr
10 Estimated Time of Death Livor Mortis or lividity: medical condition that occurs after death and results in the settling of blood in areas of the body closest to the ground. Begins immediately after death and lasts for 12 hoursAlgor Mortis: postmortem changes that cause a body to lose heat. Process in which the body continues to cool to room temperature. 1 – 1.5 degree/hour
11 Forensic EntomologyStudy of insects and their relation to a criminal investigationAfter decomposition begins, insects such as blow flies are the first to infest the body
12 Arriving at the Crime Scene Secure and isolate the crime sceneDetermine boundaries of crime scene and priorities for evidence collectionRough sketchFinished sketchPhotographVideotapingNotes
13 Collecting EvidenceConduct a systematic search for evidence; be unabiased and thorough.Field techniciansWhat to look for depends on the crime and what specific locations of the crime scene would most likely be affectedMicroscopic or massive objectsCollect carriers of possible evidenceVacuum or sweeping collected
14 Packaging of EvidencePrevent any changes from occurring (contamination, breakage, evaporation, bending, loss)Process trace evidence from original object (shirt, shoe) rather than isolating and packaging if possiblePackage evidence separately
15 Chain of custodyContinuity of possession; every person who touched it must be accounted forStandards for collecting, labeling, and submitting evidence forms are necessary for courtLabels include collectors initials, location of evidence, date of collection. Identification numbers must also be used
16 Submission of Evidence Standard/reference samplesSubstance controlsEvidence submission form will detail the evidence collect and particular type of examination/analysis requested.Lab tech not bound by requests
17 Methods of Detection Types of prints Latent printVisible print – deposited ink, blood, dirtPlastic print – impression in a soft surfaceMost natural finger prints consists of secretions of the skin’s glandsDeveloped by either powders or chemicals
18 Fingerprints History 3 Patterns Japanese used thumb print as a signature on documents until 1860.First used in crime in 1901 by Sir Edward Richard Henry3 PatternsWhorlLoopArch
19 Categories of Fingerprints Loop – ridge lines enter one side of pattern and curve around to exit from the same side of pattern. (65%)Whorl – ridge lines rounded or circular and have two deltas(30-35%)Arch – ridge lines enter print from one side and exit from the other (5%)
20 Blood EvidenceSerology: the study of antigen – antibody reactions using laboratory testsKastle-Myer Test – Is it blood?Precipitin Test – Is it human blood?DNA Analysis – Whose blood is it?
21 ABO blood typingRBCs have A, B, neither, or both antigens in its surface. Serum carries antibodies against antigens it does not have. O negative carries no Ag and therefore does not react with any Anti A, B, AB. Rh factor is a separate protein on the surface of RBCsPos reactionNeg reaction
22 Blood Splatter Analysis Location, distribution, and appearance of blood stains are an important part of forensicsInvestigators try to determine:DirectionDropping distanceAngle of impactSplatter analysis is often used for crime scene reconstruction
23 Blood Splatter Analysis Factors which influence stain patterns are:Surface textureDirection of travelPointed end of bloodstain always faces its direction of travelAngle of impact is determined by measuring the degree of circular distortion of the stainBlood striking a surface at right angles gives rise to a nearly circular stainAs the angle decreases, the stain becomes elongated in shape
Your consent to our cookies if you continue to use this website.