Forensic medicine. Dr.Eyad Abou Asali Maxillofacial sur. Ph.d

Transcription

1 Forensic medicine Dr.Eyad Abou Asali Maxillofacial sur. Ph.d

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3 Definition and scope of Forensic Science Forensic science is application of science to the law Forensic science applies the knowledge & technology of science for the definition & enforcement of such laws Forensic science is the application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system

4 History and development of Forensic Science Sir Arthur Conan Doyle popularize crime detection methods through his fictional character Sherlock Holmes

5 Mathieu Orfilia and Alphonse Bertillion

6 Mathieu Orfila & Alphonse Bertillion Father of toxicology Published first scientific treatise on the detection of poisons & their effects on animals & this established forensic toxicology as legitimate scientific endeavor Father of criminal identification First scientific system of personal identification Anthropometry used series of body measurements to distinguish individuals

7 Francis Galton, Leon Lattes & Karl Landsteiner Karl Landsteiner Francis Galton

8 Francis Galton, Karl Landsteiner & Leon Lattes First definitive study of fingerprints & developed a methodology for classifying for filing Published book titled Finger Prints & explained system for identification Lansteiner discovered blood groups; A, B, AB, O Lattes developed procedure determine blood groups from dried bloodstain

9 Calvin Goddard, Albert S. Osborn & Walter C. McCrone

10 Calvin Goddard, Albert S. Osborn & Walter C. McCrone Goddard refined techniques for comparing bullets fired using comparison microscope Osborn developed fundamental principles of document examination; authored Questioned document book McCrone pioneered use of microscope

11 Hans Gross, Edmund Locard Hans Gross Edmund Locard

12 Hans Gross Gross; First treatise describing application of scientific disciplines and scientific method to field of criminal investigation; produced a classic book called Criminal Investigation- translated in English

13 Edmund Locard He believed that when a criminal came in contact with an object, a cross-transfer of evidence occurred; Hence called Locard s exchange principle He used a couple rooms and two assistants in an attic to start the first police lab in Lyon France

14 USA 1932 first national crime lab developed in USA with the FBI by J. Edgar Hoover for all law enforcement agencies World s largest forensic laboratory & performs over a million examinations every year 1981 FBI s Forensic Science Research & Training Center 1 st time facility conduct research to develop new & reliable scientific methods applied to forensic science

15 Factors determining lab numbers increasing The demand for labs to perform drug analyses single most important factor in expansion of forensic services Also the advent of DNA profiling has caused the increase in labs & is the dominant factor in explaining how general public perceives the crime lab

16 Services of the Crime Laboratory Reasons for variations in services: Variations in local laws Different capabilities & functions of organization to which a laboratory is attached Budgetary and staffing limitations Often the sole purpose for crime lab creation has been to process drug specimens

17 Basic services provided by fullservice crime labs Physical science unit: applies principles and techniques of chemistry, physics & geology to evidence evaluation; examinations of soil, drugs, glass, paint, explosives etc are examined Biology unit: applies principles and techniques to identify DNA for profiling, stains & body fluids, hair & fiber comparison, wood and plants

18 Basic crime lab Firearms unit: examination of firearms, discharged bullets, cartridge cases, shot gun shells, ammunitions, garments and other objects examined to detect discharge of residues etc. Document examination unit: handwriting and typewriting on questioned documents studied; analysis of paper & ink; erasures, obliterations, document charred or burned

19 Basic crime lab Photography: examine and record evidence; digital imaging, infrared, ultraviolet, and X-ray photography techniques make invisible information visible; court room presentations

20 Optional services provided by fullservice crime labs Toxicology unit: body fluids & organs examined determine presence or absence of drugs & poisons often this is shared with the medical examiner s or coroner s office Latent fingerprint unit: examination of latent fingerprints submitted with other lab examinations

21 Optional services provided by fullservice crime labs Polygraph unit: polygraph or lie detector used primarily as a tool of the criminal investigator Voiceprint analysis unit: cases involving telephone threats, tape-recorded messages may use unit to identify persons Sound patterns are suppose to be unique to the person & and are captured on a voiceprint

22 Optional services provided by fullservice crime labs Evidence-collector unit: special trained personnel collect & preserve physical evidence collected at the crime scene

23 Functions of the Forensic Scientists Analysis of physical evidence: persons skilled in applying principles & techniques of physical & natural sciences to analysis of evidence but also aware of the demands & constraints of court system Frye vs. United States: what ever conclusions were deduced when examining evidence that method has sufficient established acceptance in particular field in which it belongs

24 Analysis of physical evidence Books and papers as well as a list of experts who have used a method presented to a court is used to fit the criteria of generally accepted by the scientific community Alternative to Frye standard is Federal rules of evidence: part of it deals with expert testimony, admissibility of all evidence

25 Analysis of physical evidence continued 1993 the case of Daubert vs. Merrell Dow Pharmaceutical, Inc. the U.S. Supreme Court ruled that Frye standard or general acceptance isn t the prerequisite to admissibility of scientific evidence; some state courts may apply this ruling and use the Federal rules of evidence; trial judges are the gate keepers to determine the admissibility of scientific evidence; good case for this ruling: Coppolino vs. State

26 Provision of Expert Testimony Person convinces a trial judge he/she has possesses a skill or knowledge in a trade or profession aid court in determining truth of matters at issue considered expert witness; knowledge obtained by experience, training, education or combination qualification expert witness; opposing attorney allowed cross examine witness to maybe poke holes testimony

27 Expert witness examples

28 Training Proper Recognition, collection & preserving evidence Specially training personnel to recognize, collect and preserve physical evidence is highly valued since without them, evidence could be useless Police officers or detectives are often trained by forensic scientists to know what to look for

29 Other forensic science services Forensic pathology: involves investigation of sudden, unnatural, unexplained, or violet deaths; medical examiners or coroners & answer questions like who is the victim, what injuries are present, when did the injuries occur, why and how were the injuries produced. Primary roll is to determine cause of death & by autopsy

30 Forensic pathology A medical examiner maybe able to determine time of death by evaluating stage of death of victim; immediately after death rigor mortis sets in, appears 1 st 24 hrs & disappears after 36 hrs; livor mortis also sets in and blue to black color appears on body closed to ground; can be used to determine if body moved after death; algor mortis sets in as body loses heat to the ambient room temperature

31 Forensic pathology Time of death also determined by examining potassium levels in ocular fluid The rate at which potassium is released into the vitreous humor maybe used Also examining stomach can help note what the victims last meal was

32 Forensic Anthropology Concerned with the identification and examination of human skeletal remains Examination of skeletal remains reveal their origin, sex, approximate age, race, skeletal injury Used to identify victims of mass disasters

33 Forensic Entomology Study of insects and their relationship to criminal investigation Used to estimate the time of death when it circumstances surrounding crime unknown Blow flies first arrive when body starts to decompose; eggs are laid, and maggots or fly larvae Larvae consume tissue & organs

34 Forensic Entomology Identification of specific insects present in body and approximate how long body left exposed by examining the stage development of fly larvae; weather conditions and geography affects results

35 Forensic entomology continued

36 Forensic psychiatry Relationship between human behavior and legal proceedings examined; Civil cases determine people competent to make decisions about wills, settling property or refusing medical treatment Criminal cases- evaluate behavioral disorders and determine if people are competent to stand trial; also behavioral patterns of criminals determine profile

37 Forensic Odontology Identification of victims body is left unrecognizable state Teeth enamel, hardest substance in body Use dental records such as x-rays, dental casts or photograph of person s mouth comparison made between dental remains & suspect victim Use bite marks in some cases like assault

38 Forensic engineering Failure analysis, accident reconstruction and causes and origins of fires or explosions; auto, plane and others involved Questions asked How did an accident or structural failure occur? Were the parties involved responsible If so, how were they responsible

39 Lecture: Forensic Evidence Physical Evidence Any material either in gross or trace quantities that can establish through scientific examination and analysis that a crime has been committed.

40 Forensic laboratories Items of physical evidence identification evaluation individualization

41 Classification of Physical Evidence Trace evidence Direct evidence extremely small items stands on its own to prove an alleged fact Prima facie evidence evidence established by law Circumstantial evidence incriminates a person Exculpatory evidence helps to prove that an accused individual is not guilty

42 Physical evidence utilization in other areas of forensic investigation Provides investigative leads for a case Ties one crime to a similar crime or connects one suspect with another Corroborates statements from witnesses to or victims of a crime The elements of a crime help to determine what will be useful as evidence. Besides knowing what types of evidence to search for, it is necessary to know where evidence is most likely to be found.

43 Characteristics of evidence Class characteristics features that place the item into a specific category Individual characteristics features that distinguish one item from another of the same type E x a m in a tio n a n d a n a ly s is o f p h y s ic a l e v id e n c e H ig h e s t d e g r e e o f s c ie n t ific c e r ta in t y p o s s ib le w ith c u r r e n t t e c h n o lo g y p h y s ic a l id e n tific a tio n c h e m ic a l id e n tific a tio n b io lo g ic a l id e n tific a tio n

44 diffuse reflectance spectroscopy Fibers Composition FT-IR microscopy Physical properties Solubility, melting point Glass Refractive index Microscopy Magnesium Atomic absorption spectrophotometry Shoes Miscellaneous Solidphase extraction; LC Powder Drugs of abuse FT- IR

45 Evidence Techniques Gunshot residue Atomic absorption spectrophotometry, scanning electron microscopy Clothing Visible reflectance, FT-IR microscopy, FT- Raman Pen inks UV vis, LC Plastic fragments FT-IR, UV vis Tire fragments Thermal analysis, FT-IR Food (poisoned) Liquid- and solid-phase extraction, GC/MS Fingerprints Fluorescent visualization Metals Atomic absorption spectrophotometry, titrations

46 Types of physical evidence BODY FLUIDS Conventional serology: presence of blood in stains species identification and ABO grouping is not adequately informative to positive identify a person DNA analysis can associate victim and/or suspect with each other or with the crime scene BLOODSTAIN PATTERNS additional information SEM: erythrocytes & lymphocytes

47 Types of physical evidence BODY TISSUES organ samples collected at autopsy, including blood, urine and stomach contents toxicological analysis volatile compounds (ethanol, methanol, isopropanol) heavy metals (arsenic) nonvolatile organic compounds (drugs of abuse, pharmaceuticals) miscellaneous (strychnine, cyanide) DRUGS & CONTROLLED SUBSTANCES trace drug presence, identity, and quantity plant materials, powders, tablets, capsules Black tar heroine wrapped in cellophane

48 Types of physical evidence DOCUMENTS examination typed, handwritten and printed materials for evidence of forgery indented writings, obliterated or altered writings, used carbon paper, burned or charred paper paper and ink analysis handwriting comparison to determine authenticity Obliterated writing examination

49 Types of physical evidence HAIRS hairs analysis can determine morphological features DNA analysis toxicological examination FIBERS human/animal race body area cosmetic treatments method of removal (crushed, cut, burned, forcibly removed, fallen out naturally) can associate a hair to a person positive identification presence of drugs and poisons type color, composition construction

50 Types of physical evidence Two matching hairs identified with the comparison microscope Flax fibers viewed with polarized light

51 Types of physical evidence FINGERPRINTS the strongest possible evidence of a person s identity FIRE DEBRIS & EXPLOSIVES RESIDUE EXAMINATIONS identification of accelerants and explosive residues Fingerprint Matching Unburned accelerator liquid on a soot covered carpet

52 Types of physical evidence FIREARMS & AMMUNITION individual microscopic marks identification, source, operability of firearms. detection and characterization of gunpowder residues muzzle-to-garments distance estimation GLASS FRAGMENTS Cause of breakage Direction of breakage force Physical fitting Glass fragment comparisons Photomicrograph: test bullet - questioned bullet Glass fracture produced by a high-speed projectile

53 Types of physical evidence PAINT & PAINT PRODUCTS analysis and comparison of paint transferred from the surface of an object to another during the commission of a crime: Suspect vehicle impacting a victim vehicle; a pedestrian or a stationary object Tool impacting stationary object Paint databases can help identify the year, make and/or color of a motor vehicle from a chip of paint left at the scene. Paint Layers on Wood Surface

54 Types of physical evidence TOOLMARK IDENTIFICATION microscopic side-by-side comparison attempts to link a particular tool with a particular mark to the exclusion of any other tool ROPE & CORDAGE composition, construction, color and diameter Spacing between teeth in gripping -major role in toolmark examinations manufacturer

55 Types of physical evidence SOILS & MINERALS comparison between two or more soils to determine if they share a common origin color, texture, composition comparison WOOD place the suspect at the crime scene side or end matching, fracture matching and species identification. Layers of soil exposed at a grave site. Each layer must be sampled Cross-section - Xylem

56 Types of physical evidence OILS/GREASE & COSMETIC PRODUCTS possess unique composition for comparison SHOEPRINTS & TIRE TREAD IMPRESSIONS have value for forensic comparisons. Shoeprint collected using a gelatin lifter. can provide positive identification of the suspect s shoes or tires from the suspect s vehicle.

57 Processing physical evidence discovering, recognizing and examining it; collecting, recording and identifying it; packaging, conveying and storing it; exhibiting it in court; disposing of it when the case is closed.

58 The Crime Scene

59 Physical Evidence Physical evidence is any object that can establish that a crime has been committed or can link a crime and its victim or its perpetrator. Forensic science begins at the crime scene. The investigator must recognize physical evidence & properly preserve it for laboratory examination. The evidence must be kept in its original condition as much as possible.

60 Securing the Crime Scene Secure & Isolate the Crime Scene First priority is medical assistance to individuals & arresting the perpetrator. Ropes or barricades and guards will prevent unauthorized access to the area. Every person who enters the crime scene has the potential to destroy physical evidence. The lead investigator evaluates the scene & determines the boundaries. They do an initial walk through & develop a strategy. All items must be documented & photographed.

61 Recording the Crime Scene 3 methods of crimescene recording: photography, sketches, & notes Ideally all 3 should be used

62 Photography The crime scene should be unaltered, unless injured people are involved, objects must not be moved until they have been photographed from all necessary angles. If things are removed, added, or positions changed the photographs may not be admissible evidence. Photograph completely Area where crime took place & adjacent areas Various angles

63 Photography If crime scene includes a body: Take photos to show body s location & position relative to the whole crime scene Take close-up photos of injuries & weapons lying near the body After the body is removed, photograph the surface underneath. When size is significant, use a ruler or other measuring scale Digital cameras allow for enhancement & examination in fine detail. Videotaping a scene is also becoming popular.

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65 Sketches Once photos are taken, sketch the scene. A rough sketch is a sketch, drawn at the crime scene, that contains an accurate depiction of the dimensions of the scene & shows the location of all objects having a bearing on the case. All measurements are made with a tape measure Show all items of physical evidence Assign each item a number or letter and list it in the legend Show a compass heading designating north A finished sketch is a precise rendering of the crime scene, usually drawn to scale. Computer-aided drafting (CAD) has become the standard.

66 Rough-sketch diagram of a crime scene. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C.,

67 Finished-sketch diagram of a crime scene. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C.,

68 Notes Note taking must be a constant activity throughout the processing of the crime scene. The notes may be the only source of information to refresh memory. Tape-recording notes at a scene can be advantageous detailed notes can be taped much faster than they can be written.

69 Dealing with Physical Evidence Once found, physical evidence must be collected & stored in a way that preserves its integrity for forensic comparison & analysis. The search for physical evidence must be thorough and systematic, even when suspects are immediately seized. A forensic scientist is not usually needed at the scene unless the evidence is complex or it is a major crime. Some police agencies have trained field evidence technicians.

70 Searching the Crime Scene One person should supervise & coordinate. Include all probable entry & exit points in search What to search for will be determined by the particular circumstances of the crime. Examples Homicide Hit-and-run In most crimes, a search for latent fingerprints is required.

71 Systematic Search

72 Collect Physical Evidence Physical evidence can be anything from massive objects to microscopic traces. It may be necessary to take custody of all clothing worn by the participants in a crime. Handle carefully & wrap separately to avoid loss of trace evidence. Critical areas of the crime scene should be vacuumed & the sweepings submitted to the lab for analysis. Mobile crime-scene vehicles carry supplies to protect the crime scene; photo, collect, & package evidence; & develop latent fingerprints.

73 Collect Physical Evidence The integrity of evidence is best maintained when the item is kept in its original condition as found at the crime scene. The entire object should be sent to the lab. If evidence is found adhering to a large structure, remove specimen with forceps or other appropriate tool. In the case of a bloodstain, one may either scrape the stain off the surface, transfer the stain to a moistened swab, or cut out the area of the object containing the stain.

74 Collect Physical Evidence Each different item or similar items collected at different locations must be placed in separate containers. Packaging evidence separately prevents damage through contact and prevents cross-contamination.

75 Autopsy Room Medical examiner or coroner carefully examines the victim to establish a cause & manner of death. Tissues are retained for pathological & toxicological examination. The following are collected & sent to the lab: Victim s clothing Fingernail scraping Head & pubic hairs Blood (DNA typing) Vaginal, anal, & oral swabs (in sex-related crimes) Recovered bullets from the body Hand swabs from shooting victims (for GSR analysis)

76 Forceps Tools for Evidence Collection Unbreakable plastic pill bottles w/ pressure lids Manila envelopes, glass vials, pill boxes Paper bags are better than plastic why? Fire evidence must be kept in an airtight container to prevent evaporation of petroleum residues Clothing must be air-dried & placed in individual paper bags.

77 Chain of Custody Chain of custody is a list of all people who came into possession of an item of evidence. Chain must be established whenever evidence is presented in court as an exhibit. Failure to do so may lead to? Regarding authenticity & integrity of evidence. All items should be carefully packaged and marked upon their retrieval at crime sites. Normally, the collector s initials & date of collection are inscribed directly on the article. The evidence container must also be marked with collector s initials, location of evidence, & date of collection.

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