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  • Forensic Biology

    jing qiang

  • ContentEvidenceBiologic EvidencePersonal Identification Theory

  • What happened ?

  • Cases: XX year XX in the province, a bombing occurred, several people died and injured. Scene investigation found that, in the bombing field, there is a point where a bottle of mineral water was found. Except for that, nothing else is informative.

  • Problems

    1The crime scenes were an accident or a manmade one?2Who did this?3How to collect evidence associated with the problem?4What kinds of evidences are to collect5What we are doing ?

  • *CRIME+=What Happened?Why Did ItHappened?Who DidIt?Crime Scene Evidence Collection Witness, Suspect and Motive DevelopmentPost Scene Evidence Processing Cause, manner, time of deathInvestigative Stage Profiling

    Means Motive OpportunityIdentificationand Arrest ofSuspect

  • *Forensic PathologyInvestigation of sudden unnatural, unexplained or violent deathsAnswer the questions:Who is the victim?What are the injuries, when did they occur, and how were they produced?5 manners of death: natural, homicide, suicide, accident, undetermined

  • Forensic Biology Study blood, semen, saliva and other bodily fluids for use in legal cases

    Extract DNA from blood for cross reference and case use

    Analyze blood stain patterns

  • Nature of Biologic EvidenceBlood may be encountered as physical evidence in:

    HomicidesSexual AssaultVehicular hit-and-runBurglaryOther crimes

  • *What we are doingIndividualization--demonstrating that the sample is unique, even among members of the same class.Interpretation--gives meaning to all the informationReconstruction--reconstructs the case eventsLee, Dr. Henry. Famous Crimes. Southington:Strong Books, 2001

  • Locating Biological EvidenceYour Eye TouchHi-Intensity & Alternate Light SourcesChemical TestsEnzymatic Tests Immunological Tests

  • *Just A ThoughtIts not what you know that hurts you, its what you think you know and its not so . . .Mark Twain

    How does this apply to forensic science and crime investigations?

  • * Evidence CharacteristicsClass--common to a group of objects or persons

    Individual--can be identified with a particular person or source.ABO Blood TypingBlood DNA Typing

  • Preliminary Considerations

    Before a crime scene investigator begins documenting and collecting biologic evidence, he/she must recognize the value of biologic evidence and how it fits in the overall events associated with the crime.

  • Preliminary Considerations

    It is essential to document, collect, and preserve biologic evidence.

    Improperly collected and preserved biologic evidence can weaken or destroy a potential source of facts in a case.

  • Preliminary ConsiderationsBiologic evidence can point the investigator in the right direction for investigative purposes

    If the evidence is collected and stored suitably, it can be presented to a judge or jury several years from the time of the criminal act.

  • Preliminary ConsiderationsProperly collected and preserved biologic evidence can establish a strong link between an individual and a criminal act.

    Biologic evidence or the lack of biologic evidence can bolster or contradict a witness statement or any statements the suspect may have made.

  • Preliminary ConsiderationsThe most common applications of biologic evidence are:

    Finding blood with the victims genetic markers (ABO blood type, DNA profile, etc) on the suspect, on something in the suspects possession, or something associated with the suspect (such as the suspects fingerprints).

  • Preliminary Considerations

    Finding blood with the suspects genetic markers on the victim, on something in the victims possession, or something associated with the victim.

  • Nature of Blood EvidenceBloodstain evidence has two primary categories of examination importance to the crime scene investigator:

    A. Bloodstain pattern interpretation

    B. Genetic Marker Typing

  • Preliminary ConsiderationsPresently, the courts do not recognize biologic evidence as evidence that can be absolutely linked to an individual, such as fingerprints, bite marks, broken fingernails, and handwriting.

    If DNA analysis is utilized, then biologic evidence falls into the category of evidence that can be linked to an individual with a very high degree of probability.

  • Blood Pattern InterpretationMay establish whether or not a crime occurred (murder vs. suicide or accident)

    May dispute or corroborate witnesses statements.

    Can determined from whom the bloodstain pattern emanated. (genetic marker typing)

  • Biology UnitApplies the knowledge of biological sciences in order to investigate blood samples, body fluids, hair, and fiber samples

  • Nature of Blood EvidenceThe identity and typing of bloodstains canAssist in establishing elements of the crimeCan identify or eliminate a suspectCan be used to corroborate or dispute the statements of principals when the bloodstains play a part in a reconstruction of the crime.

    The proper collection is essential to the quantity and the quality of information from the stains

  • Disciplines namedForeign (forensic serology) (forensic blood group serology) (forensic hematogenetics) (forensic genetics) (forensic biology)

    China The forensic professional directory named Forensic Biology

  • Section 1 physical evidence and forensic evidence

  • Common Examples of Physical EvidenceBlood, Semen, SalivaHairSamples from body organsFingerprintsDocumentsSerial numbersImpressionsglassSoil & mineralsFibersPetroleum residuesPaint, plastic & rubberPowder residueFirearms & explosivesWood & vegetative fragments

  • Evidence The evidence of all the facts that proves the true situation.The Evidence has two fundamental characteristics:1. An objectives existence, traces, articles, documents, sound, video, etc.2. The relationship with the facts of the case have the facts objectively

  • Evidence of the Criminal Procedure Law Evidence, documentary evidence The testimony of witnesses Statements of victims The suspect, the confession of the accused and excuse Expert conclusions Record of inspection Audio-visual materialsEVIDENCE

  • Evidence: Refers to the characteristics of the material themselves has to prove the goods and material traces of the real situation of the case. As an independent form of evidence, physical evidence has different characteristics than other evidence.

  • Evidence to prove the facts of the case by its material characteristics Evidence of indirect proof of the facts of the case

  • For example: a gold shop was stolen and on fire, effective evidence cannot be found due to the fire scene. But the gold shop located at a crossroad, traffic video at that night was available. Investigators brought up the video, a man was seen pushing a bicycle through the crossroads, and tried to pull over to walk by the sideway just before the accident, in the middle of the night. Unfortunately a car just passed by and the light of the car made the look of the man present in the video. According to the analysis of the tape, investigators found out the identity of the man, and cracked down on the theft of the case.

  • Evidences are less susceptible to subjective factors

    Paternity testing, through the analysis of genetic markers, the paternity relationship can be confirmed or excluded.

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  • Evidence to prove the facts of the case by its material characteristics

    External characteristics: shape, color, quantity, weight, and the placing of a location. Internal characteristics: physical, chemical, biological structure, composition, characteristics, and so on.

  • Item evidenceTraces of evidenceInstruments and material evidenceAudio and video evidenceChemical evidenceBiological EvidenceClassification

  • *Biological EvidenceBloodSemenSalivaSweat/TearsHairBoneTissuesUrineFecesAnimal Material InsectsBacterial/Fungal

  • Forensically Important Biological SubstancesWhat are the they?BloodSemenSalivaUrineFecesVomitFingerprint residueSloughed off cellsWhat else?BacteriaPlant materialPollenViruses

  • Biological Evidence related with the human body is often referred to as forensic evidence to prove the facts of the case, its biological composition and properties.The evidence often require inspection and identification to find them with the facts of the case.

  • Nature of Biologic EvidenceBiologic evidence may be encountered as physical evidence in:

    HomicidesSexual AssaultVehicular hit-and-runBurglaryOther crimes

  • Preliminary ConsiderationsBiologic evidence can point the investigator in the right direction for investigative purposes

    If the evidence is collected and stored suitably, it can be presented to a judge or jury several years from the time of the criminal act.

  • The characteristics of Forensic evidence1Its scientific evidence2. Influenced by environmental factors3. Its biological samples 4. we have to design reasonable analysis strategy, select the correct experimental methods.

  • Biologic Evidence

    It is essential to document, collect, and preserve biologic evidence.

    Improperly collected and preserved biologic evidence can weaken or destroy a potential source of facts in a case.

  • Biologic EvidenceBiologic evidence can point the i