Elements Of Forensic Science


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Elements Of Forensic Science

  1. 1. Elements of Forensic Science Types of Evidence Related Services
  2. 2. Elements of Forensic Science <ul><li>Firearms and Toolmark Identification </li></ul><ul><li>Forensic Psychiatry and Profiling </li></ul><ul><li>Questioned Document Examination </li></ul><ul><li>Criminal Law </li></ul><ul><li>Careers in Law Enforcement </li></ul><ul><li>Forensic Photography </li></ul><ul><li>Personal Identification </li></ul><ul><li>Crime Scene Processing </li></ul>
  3. 3. Firearms and Toolmark ID <ul><li>ballistics and bullet matching </li></ul><ul><ul><li>each firearm has it’s own “signature” in the rifling in the barrel </li></ul></ul><ul><ul><ul><li>lands and grooves spiral down the barrel </li></ul></ul></ul><ul><ul><ul><li>soft lead is forced into these areas creating microscopic scratches thus marking the bullet </li></ul></ul></ul>
  4. 4. Firearms and Toolmark ID <ul><li>ballistics and bullet matching </li></ul><ul><ul><li>these scratches are unique to one particular firearm </li></ul></ul><ul><ul><li>tested in lab by firing a bullet through the suspect weapon </li></ul></ul><ul><ul><ul><li>test fired bullet compared to crime scene bullet </li></ul></ul></ul><ul><ul><ul><li>if striations(scratches) line up – a positive match is made </li></ul></ul></ul><ul><ul><ul><li>if striations don’t line up, result is negative </li></ul></ul></ul>
  5. 5. Firearms and Toolmark ID <ul><li>ballistics and bullet matching </li></ul><ul><ul><li>much debate about “ballistic fingerprinting” </li></ul></ul><ul><ul><ul><li>barrels can be changed out completely or filed down </li></ul></ul></ul><ul><ul><ul><li>barrels and firing pins also wear with time changing the “fingerprint” </li></ul></ul></ul><ul><ul><ul><li>firing pins can be easily modified </li></ul></ul></ul>
  6. 6. Firearms and Toolmark ID <ul><li>imprint evidence </li></ul><ul><ul><li>two types </li></ul></ul><ul><ul><ul><li>three dimensional ex. car tire in mud </li></ul></ul></ul><ul><ul><ul><li>two dimensional ex stepping in paint </li></ul></ul></ul><ul><ul><ul><ul><li>this type leaves two imprints – one in the paint (a negative image) and one from the bottom of the shoe onto a new surface (like a rubber stamp) </li></ul></ul></ul></ul><ul><ul><ul><li>can be so detailed it can be used to identify class and individual characteristics </li></ul></ul></ul>
  7. 7. Firearms and Toolmark ID <ul><li>imprint evidence </li></ul><ul><ul><li>tire impressions </li></ul></ul><ul><ul><ul><li>tread evidence </li></ul></ul></ul><ul><ul><ul><li>pattern of long tire impression can yield additional information </li></ul></ul></ul><ul><ul><ul><ul><li>wheel base distance </li></ul></ul></ul></ul><ul><ul><ul><ul><li>direction car facing </li></ul></ul></ul></ul><ul><ul><ul><ul><li>how they pulled out </li></ul></ul></ul></ul><ul><ul><ul><ul><li>direction of travel </li></ul></ul></ul></ul>
  8. 8. Firearms and Toolmark ID <ul><li>toolmark identification </li></ul><ul><ul><li>three types of toolmark impressions </li></ul></ul><ul><ul><ul><li>compression – a tool surface presses into a softer material </li></ul></ul></ul><ul><ul><ul><li>sliding – a tool scrapes across a surface causing parallel striations </li></ul></ul></ul><ul><ul><ul><li>cutting – a combination of the two </li></ul></ul></ul><ul><ul><li>all three types can yield class and individual characteristics </li></ul></ul>
  9. 9. Firearms and Toolmark ID <ul><li>explosives </li></ul><ul><ul><li>residue can be analyzed to determine type of explosive </li></ul></ul><ul><ul><ul><li>some manufacturers are putting chemical tags in their explosives that allow for tracking of specific batches </li></ul></ul></ul><ul><ul><li>detonator can be analyzed for origin of component parts </li></ul></ul>
  10. 10. Forensic Psychiatry& Profiling <ul><li>forensic psychiatry </li></ul><ul><ul><li>serves to define </li></ul></ul><ul><ul><ul><li>what mental illness and disorder are </li></ul></ul></ul><ul><ul><ul><li>what creates mental illness and disorder </li></ul></ul></ul><ul><ul><ul><li>how they are diagnosed </li></ul></ul></ul><ul><ul><ul><li>how they are treated </li></ul></ul></ul>
  11. 11. Forensic Psychiatry& Profiling <ul><li>forensic psychiatry </li></ul><ul><ul><li>mental illness – the individual does not function well because of emotional fluctuations or distorted point of view interpretation </li></ul></ul><ul><ul><li>mental disorder – clinically significant behavior or psychological syndrome or pattern that is associated with present distress or disability or with a significantly increased risk of suffering death, pain or disability or loss of freedom </li></ul></ul>
  12. 12. Forensic Psychiatry& Profiling <ul><li>forensic psychiatry </li></ul><ul><ul><li>issue of incompetency is fitness to stand trial </li></ul></ul><ul><ul><ul><li>must understand what is going on </li></ul></ul></ul><ul><ul><ul><li>can help in their own defense </li></ul></ul></ul><ul><ul><ul><li>three bases of incompetency </li></ul></ul></ul><ul><ul><ul><ul><li>emotional/psychological factors </li></ul></ul></ul></ul><ul><ul><ul><ul><li>cognitive or intellectual factors </li></ul></ul></ul></ul><ul><ul><ul><ul><li>physical factors </li></ul></ul></ul></ul><ul><ul><ul><li>competency evaluation must be done – cannot be refused </li></ul></ul></ul>
  13. 13. Forensic Psychiatry& Profiling <ul><li>forensic psychiatry </li></ul><ul><ul><li>issue of insanity applies to mental state of defendant at time at which the crime was committed </li></ul></ul><ul><ul><ul><li>defendant must concede guilt at time of insanity plea </li></ul></ul></ul><ul><ul><ul><li>defendant must be competent to stand trial </li></ul></ul></ul><ul><ul><ul><li>defendant must prove profound defect of mental ability – this must be directly related to the crime </li></ul></ul></ul>
  14. 14. Forensic Psychiatry& Profiling <ul><li>profiling </li></ul><ul><ul><li>process by which trained forensic psychologist sifts through aspects of the crime to develop a description of the personality of the perpetrator </li></ul></ul><ul><ul><li>“ Behavior reflects personality.” (John Douglas, Mindhunter ) </li></ul></ul><ul><ul><li>process works because of extensive database </li></ul></ul><ul><ul><ul><li>interviews of hundreds of convicted serial killers, serial rapists, and mass murderers </li></ul></ul></ul>
  15. 15. Forensic Psychiatry& Profiling <ul><li>profiling </li></ul><ul><ul><li>description can include </li></ul></ul><ul><ul><ul><li>age </li></ul></ul></ul><ul><ul><ul><li>sex </li></ul></ul></ul><ul><ul><ul><li>occupation </li></ul></ul></ul><ul><ul><ul><li>behavioral disorders </li></ul></ul></ul><ul><ul><ul><li>upbringing </li></ul></ul></ul><ul><ul><ul><li>marital status </li></ul></ul></ul><ul><ul><ul><li>type of living quarters and general condition </li></ul></ul></ul><ul><ul><ul><li>type of person the perpetrator lives with </li></ul></ul></ul><ul><ul><ul><li>what type of car is driven </li></ul></ul></ul><ul><ul><ul><li>any disability or difficulty in relating to others </li></ul></ul></ul><ul><ul><ul><li>how the crime was committed </li></ul></ul></ul>
  16. 16. Forensic Psychiatry& Profiling <ul><li>profiling </li></ul><ul><ul><li>description can be used to </li></ul></ul><ul><ul><ul><li>focus investigation on particular suspects </li></ul></ul></ul><ul><ul><ul><li>provide strategies on how to approach suspect during interrogation </li></ul></ul></ul><ul><ul><ul><li>provide strategies on how to break him down on the witness stand at the trial </li></ul></ul></ul><ul><ul><li>Criminal Minds </li></ul></ul>
  17. 17. Questioned Document Analysis <ul><li>handwriting analysis </li></ul><ul><ul><li>examination of design, shape and structure </li></ul></ul><ul><ul><li>determine authorship </li></ul></ul><ul><ul><li>basic principle is that no two people will write the exact same thing in the exact same way </li></ul></ul>
  18. 18. Questioned Document Analysis <ul><li>handwriting analysis </li></ul><ul><ul><li>characteristics </li></ul></ul><ul><ul><ul><li>letter formations </li></ul></ul></ul><ul><ul><ul><li>connectors </li></ul></ul></ul><ul><ul><ul><li>upstrokes </li></ul></ul></ul><ul><ul><ul><li>retraces </li></ul></ul></ul><ul><ul><ul><li>down strokes </li></ul></ul></ul><ul><ul><ul><li>spacing </li></ul></ul></ul><ul><ul><ul><li>baseline </li></ul></ul></ul><ul><ul><ul><li>curves </li></ul></ul></ul><ul><ul><ul><li>size </li></ul></ul></ul><ul><ul><ul><li>distortions </li></ul></ul></ul><ul><ul><ul><li>hesitations </li></ul></ul></ul><ul><ul><ul><li>flying stops </li></ul></ul></ul>
  19. 19. Questioned Document Analysis <ul><li>typewriting </li></ul><ul><ul><li>much like firearms, typewriters of the same make and model are pretty much the same </li></ul></ul><ul><ul><li>daily wear and tear or parts of the machining process can cause “defects” or individual characteristics that translate to paper when the machine is used </li></ul></ul>
  20. 20. Questioned Document Analysis <ul><li>photocopiers and laser printers </li></ul><ul><ul><li>in photocopier, original is placed on glass and exposed using reflected light to a drum that is covered with photosensitve material </li></ul></ul><ul><ul><li>image of original exists on drum as invisible positive photoelectric charge </li></ul></ul><ul><ul><li>negatively charged toner is drizzled on drum where it sticks to the positive image </li></ul></ul><ul><ul><li>paper with a positive charge passes the drum causing the negatively charged toner to transfer to the paper which is then heat sealed </li></ul></ul><ul><ul><li>with laser printer - image of the original held in memory of computer is written to the photosensitive drum using a laser </li></ul></ul>
  21. 21. Questioned Document Analysis <ul><li>photocopiers and laser printers </li></ul><ul><ul><li>paper yields clues </li></ul></ul><ul><ul><ul><li>marks from belts, pinchers, rollers and gears can be matched like toolmarks </li></ul></ul></ul><ul><ul><li>toner </li></ul></ul><ul><ul><ul><li>can have unique chemical compositions </li></ul></ul></ul><ul><ul><ul><li>how toner is placed and fused on paper (ie. clumps, blobs) </li></ul></ul></ul><ul><ul><li>marks on optics </li></ul></ul><ul><ul><ul><li>scratches or other marks on glass, lenses or mirrors will leave markings on the printed page that can be matched with the optic </li></ul></ul></ul>
  22. 22. Questioned Document Analysis <ul><li>forgery </li></ul><ul><ul><li>false making or altering of any writing with intent to defraud </li></ul></ul><ul><ul><li>four types </li></ul></ul><ul><ul><ul><li>traced </li></ul></ul></ul><ul><ul><ul><li>simulation </li></ul></ul></ul><ul><ul><ul><li>freehand </li></ul></ul></ul><ul><ul><ul><li>lifted </li></ul></ul></ul>
  23. 23. Questioned Document Analysis <ul><li>forgery </li></ul><ul><ul><li>traced can use </li></ul></ul><ul><ul><ul><li>overlays (like tracing paper) </li></ul></ul></ul><ul><ul><ul><li>transmitted light (as with a light board) </li></ul></ul></ul><ul><ul><ul><li>tracing indentations left in the page underneath the original </li></ul></ul></ul><ul><ul><ul><li>tracing patterns of dots that outline the writing to be forged </li></ul></ul></ul>
  24. 24. Questioned Document Analysis <ul><li>forgery </li></ul><ul><ul><li>simulation </li></ul></ul><ul><ul><ul><li>involves the copying of writing from a genuine article, trying to imitate the handwriting of the original </li></ul></ul></ul><ul><ul><li>freehand </li></ul></ul><ul><ul><ul><li>written with no knowledge of the appearance of the original </li></ul></ul></ul><ul><ul><ul><li>just writing off the top of your head and passing it off as something else </li></ul></ul></ul>
  25. 25. Questioned Document Analysis <ul><li>forgery </li></ul><ul><ul><li>lifted </li></ul></ul><ul><ul><ul><li>tape is used to lift off a signature then place it on another document </li></ul></ul></ul><ul><ul><li>detection of forgeries </li></ul></ul><ul><ul><ul><li>freehand easiest to detect </li></ul></ul></ul><ul><ul><ul><li>simulation easy to detect – style not as fluid, more hesitations than “comfortable” writing </li></ul></ul></ul><ul><ul><ul><li>traced and lifted are easy to detect but identity of forger cannot be determined </li></ul></ul></ul>
  26. 26. Questioned Document Analysis <ul><li>counterfeit security measures </li></ul><ul><ul><li>U.S. currency </li></ul></ul><ul><ul><ul><li>easy to counterfeit! </li></ul></ul></ul><ul><ul><ul><li>all paper currency after 1993 has microline printing, nylon security threads and a plastic security strip </li></ul></ul></ul><ul><ul><ul><li>as of 2000, all paper currency was updated except the $1 bill </li></ul></ul></ul>
  27. 27. Questioned Document Analysis <ul><li>counterfeit security measures </li></ul><ul><ul><li>official documents (i.e. passport) </li></ul></ul><ul><ul><ul><li>background is printed with intricate pattern of polygons with a color shift in the ink </li></ul></ul></ul><ul><ul><ul><li>green stars – reflective specks sealed in the paper </li></ul></ul></ul><ul><ul><ul><li>blue “USA” stamp overlaps photo and background paper </li></ul></ul></ul><ul><ul><ul><li>three red stars stamped over edge of photo </li></ul></ul></ul><ul><ul><ul><li>whole page sealed with single sheet of adhesive plastic </li></ul></ul></ul><ul><ul><ul><li>microline printing in lower right corner </li></ul></ul></ul>
  28. 28. Criminal Law <ul><li>serves to define offences under a codified system of laws and punishments </li></ul><ul><li>where we define what crime is and how it goes about being prosecuted </li></ul>
  29. 29. Criminal Law - Homocide <ul><li>murder (malice required) </li></ul><ul><ul><li>first degree </li></ul></ul><ul><ul><ul><li>intentional and premeditated killing </li></ul></ul></ul><ul><ul><ul><li>killing in the course of a dangerous felony </li></ul></ul></ul><ul><ul><li>second degree </li></ul></ul><ul><ul><ul><li>intentional, but not premeditated </li></ul></ul></ul><ul><ul><ul><li>intent to cause serious bodily injury resulting in death </li></ul></ul></ul><ul><ul><ul><li>death by act creating grave risk of death </li></ul></ul></ul><ul><ul><ul><li>killing in the course of other mala in se felonies </li></ul></ul></ul>
  30. 30. Criminal Law - Homocide <ul><li>manslaughter (no malice required) </li></ul><ul><ul><li>voluntary </li></ul></ul><ul><ul><ul><li>killing with the intent to kill or inflict grievous bodily injury but under the influence of passion caused by sufficient provocation </li></ul></ul></ul><ul><ul><li>involuntary </li></ul></ul><ul><ul><ul><li>negligent or reckless homocide </li></ul></ul></ul><ul><ul><ul><li>killing in the course of committing a dangerous misdemeanor </li></ul></ul></ul>
  31. 31. Criminal Law - Homocide <ul><li>justifiable homocide </li></ul><ul><ul><li>self defense </li></ul></ul><ul><ul><li>defense of others </li></ul></ul><ul><ul><li>defense of property </li></ul></ul><ul><ul><li>prevention of felonies </li></ul></ul><ul><ul><li>arresting a felon </li></ul></ul>
  32. 32. Criminal Law - Homocide <ul><li>accidental death </li></ul><ul><ul><li>duty of care </li></ul></ul><ul><ul><li>involuntary manslaughter or negligence </li></ul></ul>
  33. 33. Criminal Law – Assault and Battery <ul><li>battery </li></ul><ul><ul><li>intentional or reckless touching of another without excuse or justification </li></ul></ul><ul><ul><li>does not require significant blow that inflicts bodily injury </li></ul></ul>
  34. 34. Criminal Law – Assault and Battery <ul><li>assault </li></ul><ul><ul><li>an unlawful attempt, coupled with present ability, to commit a battery (such as a missed punch) </li></ul></ul>
  35. 35. Criminal Law – Assault and Battery <ul><li>aggravated assault and battery </li></ul><ul><ul><li>when battery inflicts a serious bodily injury or assault and battery involves the use of a deadly weapon </li></ul></ul><ul><ul><li>assault with intent to rape </li></ul></ul>
  36. 36. Criminal Law – Rape <ul><li>sexual intercourse by a male with a female, who is not his wife, achieved by force or threat of force against the will of the victim </li></ul><ul><ul><li>force can include drugs administered by the male OR inability of the victim to understand what is happening </li></ul></ul><ul><ul><li>spousal “immunity” in some old laws has been done away with </li></ul></ul><ul><ul><li>men don’t rape men – they sodomize </li></ul></ul><ul><ul><li>women may be charged with rape as a accomplice, (this too is changing) </li></ul></ul>
  37. 37. Criminal Law – Rape <ul><li>statutory rape involves sexual intercourse with a minor who is regarded by law as incapable of giving lawful consent to the act </li></ul>
  38. 38. Criminal Law – Conspiracy <ul><li>agreement between two or more people, beyond an undercover government agent, to commit an unlawful act, and some degree of intent </li></ul><ul><ul><li>ultimate act can be impossible to carry out </li></ul></ul><ul><ul><li>everyone does not have to know everyone else involved </li></ul></ul><ul><ul><li>all parties must have a common end </li></ul></ul><ul><ul><li>acts of one are acts of all </li></ul></ul>
  39. 39. Criminal Law – Conspiracy <ul><li>for conspiracy, one overt act in furtherance of the crime by any involved party gives liability </li></ul><ul><ul><li>if one abandons the conspiracy, he is still liable for the conspiracy, but not the resulting act </li></ul></ul><ul><ul><li>“ overt act” need not be criminal in itself </li></ul></ul><ul><li>individuals are charged with conspiracy and the actual crime (i.e. murder), the two don’t merge </li></ul>
  40. 40. Criminal Law – Burglary <ul><li>at common law, breaking and entering into a dwelling during the night with intent to commit a felony </li></ul><ul><ul><li>modern code includes </li></ul></ul><ul><ul><ul><li>any building or similar structure </li></ul></ul></ul><ul><ul><ul><li>day or night </li></ul></ul></ul><ul><ul><ul><li>unlawful entry </li></ul></ul></ul><ul><ul><ul><li>with or without a breaking </li></ul></ul></ul><ul><ul><li>people get robbed, not houses </li></ul></ul>
  41. 41. Criminal Law – Larceny <ul><li>taking the property of another, with knowledge of their ownership, to deprive them permanently or infringe upon their rights in a substantial way </li></ul><ul><ul><li>petit vs. grand larceny varies in $$$ amount of property </li></ul></ul><ul><ul><li>one cannot negligently steal </li></ul></ul>
  42. 42. Criminal Law – Embezzlement <ul><li>persons who lawfully received possession of the property of another and then wrongfully convert that property to their own use </li></ul><ul><ul><li>real property can be embezzled </li></ul></ul><ul><ul><li>does not require intent to permanently deprive </li></ul></ul>
  43. 43. Criminal Law – False Pretenses <ul><li>applies to persons who induce others to transfer property to them by means of misrepresentation, which must be to a material past or present fact that the seller know to be false </li></ul><ul><ul><li>does not include “seller’s talk” </li></ul></ul>
  44. 44. Criminal Law – Robbery <ul><li>a larceny with the stolen property taken from the victim in the presence of the victim and with the taking accomplished by means of force or threat of force </li></ul><ul><ul><li>crime against person and property </li></ul></ul><ul><li>Does pickpocketing constitute a robbery? </li></ul>
  45. 45. Criminal Law – Extortion <ul><li>threat of force or harm used to achieve some sort of benefit to the criminal </li></ul><ul><ul><li>truth can be used as leverage </li></ul></ul><ul><ul><li>benefit does not have to be monetary </li></ul></ul><ul><ul><li>“ blackmailing” </li></ul></ul>
  46. 46. Criminal Law – Arson <ul><li>an intentional or reckless burning or explosion of a building owned by another person or, under limited circumstances, of a building owned by the actor </li></ul>
  47. 47. Criminal Law – Solicitation <ul><li>agreement to commit a crime </li></ul><ul><ul><li>hiring individual is just as liable as the actor </li></ul></ul><ul><ul><li>merges into conspiracy </li></ul></ul>
  48. 48. Criminal Law – Aiding and Abetting <ul><li>involved prior to the crime, contributed to the act or induced the act, even if not involved in the act itself </li></ul><ul><ul><li>one who orders a crime shares the same liability as the actor </li></ul></ul>
  49. 49. Careers in Law Enforcement <ul><li>federal law enforcement </li></ul><ul><li>state agencies </li></ul><ul><li>city agencies </li></ul><ul><li>local agencies </li></ul><ul><li>private sector </li></ul>
  50. 50. Careers in Law Enforcement <ul><li>types of jobs </li></ul><ul><ul><li>investigators, officers, troopers </li></ul></ul><ul><ul><li>lab positions </li></ul></ul><ul><ul><li>support positions (clerks, evidence technicians, surveillance operations, photographers) </li></ul></ul><ul><li>education necessary </li></ul><ul><ul><li>depends on job description and agency </li></ul></ul><ul><ul><li>usually college degree to start </li></ul></ul><ul><ul><li>specialization in a field might be required </li></ul></ul>
  51. 51. Careers in Law Enforcement <ul><li>typical application process </li></ul><ul><ul><li>call agency’s personal department and ask for an application </li></ul></ul><ul><ul><li>send in and get called for initial interview </li></ul></ul><ul><ul><li>written exam – much like SAT’s </li></ul></ul><ul><ul><li>background questionnaire and check </li></ul></ul><ul><ul><li>panel interview </li></ul></ul><ul><ul><li>physical </li></ul></ul><ul><ul><li>fitness test (if in the field) </li></ul></ul><ul><ul><li>polygraph test </li></ul></ul>