Forensics

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Forensic Science

• Definition the application of technology and
  scientific principles to those civil and criminal
  laws that are enforced by police agencies in a
  criminal justice system
• This course will focus on the areas of
• Chemistry
• Biology
• Physics
• Geology
• as they pertain to crime scene evidence.

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Value of Forensic Science

• Corpus Delicti the elements of the crime. These
  are things the prosecutor must prove beyond a
  reasonable doubt. Analysis done in forensics can
  establish these elements of a crime.
• Support of Disprove Statements by witnesses,
  victims or suspects based on the physical
  evidence recovered.

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• Identify substances and or materials. Example
  identification of a controlled substance,
  accelerant, the firing of a weapon.
• Identify Persons biological evidence,
  fingerprints are all used routinely to identify
  persons in a criminal case.
• Provides investigative leads evidence collected
  is post facto (after the crime has been committed)

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• Physical evidence can provide leads and prevent
  investigations from going down the wrong path and
  wasting valuable time in finding the criminal.
• Establish Linkage or Exclusions When there are
  no witnesses or testimony to rely on physical
  evidence is all that is present to establish the
  happenings in a crime.

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Brief History

• Mathieu Orfila (1787-1853) father of forensic
  toxicology studied detection of poisons and
  their effects on animals
• 1887 Sir Arthur Conan Doyle wrote his first
  Sherlock Holmes novel, A Study in Scarlet, which
  included as of then undiscovered techniques for
  analyzing crime scenes

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Brief History

• Francis Galton (1822-1911) first person to study
  and classify fingerprints. The fingerprints of
  identical twins are different.
• J. Edgar Hoover (1932) Head of the FBI who
  organized a national laboratory that offered
  forensic services to all law enforcement
  agencies in the country

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Brief History/Introduction

• FBI Laboratory is now the worlds largest
  forensic lab performs over 1 million
  examinations per year
• States often have their own forensic labs, as do
  some counties and municipalities
• Britain has a national system of regional labs
  under the direction of the Home Office (analogous
  to FBI)

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Introduction to the Crime Laboratory

• Because there are so many labs, 320 in 2001, in
  the US, it is impossible to fit them all into a
  single model
• Labs range from 1 to more than 100 members
• Can be general or specialized depending on the
  agency that houses the lab (for example the
  Department of Justice has many labs, including
  the gigantic FBI Lab and DEA Lab)

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Accreditation

• A voluntary process sought by the laboratories
  themselves to validate the quality of their work.
• Certification there are specialty certification
  boards for each area or expertise.

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Intro to the Crime Lab

• Some crimes do not require forensic analysis, but
  all illicit drug related crimes require analysis
• Drug related crime increases beginning in the
  1960s have resulted in a large increase in the
  number of labs

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Intro to the Crime Lab

• More recently, DNA analysis has become standard
  practice in forensics, and has also fueled this
  increase
• Labs that conduct DNA analysis must have state of
  the art facilities due to the technically
  sophisticated nature of the work

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Common Services of the Crime Lab

• Basic Services
• Physical Science Unit
• Biology Unit
• Firearms Unit
• Document Examination Unit
• Photography Unit

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Physical Science Unit

• Applies techniques of chemistry, physics, and
  geology to the identification and comparison of
  crime scene evidence
• Also may include specialists to ID illicit drugs,
  soil and minerals, and other trace physical
  evidence

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Biology Unit

• Staffed by biologists and biochemists
• Used primarily for ID of DNA, blood, and other
  bodily fluids
• Also for ID of plant materials, and human and/or
  animal hair fibers

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Firearms Unit

• Analyzes discharged bullets, cartridge casings,
  shotgun shells, and other firearms related
  evidence
• Clothing is also examined for traces of discharge
  residues (gun powder)

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Document Examination Unit

• Catch Me if You Can
• Authenticity of documents are determined by
  examining handwriting, printing, typewriter, etc.
• Other evidence comes from the types of ink and
  paper used, and the indentations made into the
  paper

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Photography Unit

• Uses high tech analytical methods to reveal
  evidence that is not visible to the naked eye,
  such as
• IR (Infra Red)
• UV (Ultra Violet Radiation)
• X-ray

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Optional Services

• Toxicology Unit
• Latent Fingerprint Unit
• Polygraph Unit
• Voiceprint Analysis Unit
• Evidence Collection Unit

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Toxicology Unit

• Bodily fluids are analyzed for the presence of
  drugs and poisons
• This unit can also be associated with the Medical
  Examiners Office
• Driving Under the Influence (DUIs) is often
  determined in the field using a breathalyzer

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Latent Fingerprint Unit

• Fingerprinting has become the method of choice
  for identification of an individual
• Latent capable of becoming visible, but not
  currently visible.
• This unit processes and analyzes fingerprints.
  There is a national database established for
  fingerprints. The AFIS Automated Fingerprint
  Identification System

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Finger print with points
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Finger print
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Polygraph Unit

• Lie detectors are used to measure heart rate and
  blood pressure in order to determine if a suspect
  is telling the truth
• Can result in both false positives (truth tellers
  accused of lying) and false negatives (liars who
  are able to beat the machine)

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Voiceprint Analysis Unit

• Examines recorded voices to determine if evidence
  is valid
• Often uses a spectrograph, which displays sound
  graphically (voiceprint)

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Evidence Collection Unit

• Many labs dispatch specially trained personnel to
  a crime scene to collect and preserve physical
  and biological evidence that will be processed
  back at the lab.
• Evidence is submitted faster than can be analyzed
  and returned.
• There is a triage approach to evidence analysis.

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Cases viewed as more serious such as murder or
sexual assault move to the front of the line, as
well as those cases going to trial.
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Expert Testimony

• Expert witness must prove to the judge that they
  possess a particular skill or have knowledge in a
  profession that will help the court
• Defense has the opportunity to cross examine
• Even expert testimony is not 100 reliable

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Other Forensic Science Services

• Forensic Pathology
• Forensic Anthropology
• Forensic Entomology
• Forensic Psychiatry
• Forensic Odontology
• Forensic Engineering

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Forensic Pathology

• Investigation of sudden, unnatural, unexplained
  or violent deaths
• Medical examiners or coroners will conduct an
  autopsy to determine cause of death.
• Postmortem toxicology results, the scene, results
  of the investigation, other forensic results are
  used to draw a likely conclusion.

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Forensic Pathology

• Stages of decomposition after death
• Rigor mortis after death, muscles relax then
  become rigid
• Useful for determining time of death
• Livor mortis blood begins to settle in parts of
  the body closest to the ground skin appears
  dark blue
• Useful for determining if body was moved after
  death

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Forensic Pathology

• Algor mortis body temp cools after death until
  it reaches room temp
• Also useful for time of death estimate

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Forensic Anthropology

• Examination of human skeletal remains and
  comparison with ante mortem x-rays to help
  identify a victim.
• Male and female differences in bones (EX. female
  pelvis is wider for child birth)
• Broken bones can aid in identification

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skulls
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Forensic Entomology

• The study of insects in relation to a criminal
  investigation
• Life cycle of insects that are well known
  provides information about time of death,
  location of death and possible movement of the
  body.
• The scientist can back calculate the times
  involved.

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Life cycle of insect
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Forensic Psychiatry

• Studies the relationship between human behavior
  and legal proceedings
• Used to determine if a suspect is competent to
  stand trial (EX. Insanity defense)
• Evaluate juveniles to help the court determine
  the best placement for the individual

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• Profilers can sometimes provide useful
  information about the characteristics of an
  unidentified offender based on the modus operandi
  (MO), habits, and crime scene patterns.
• Profilers concentrate on solving serial criminals
  such as murderers and rapists

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Forensic Odontology

• 1. Provide info for ID of victims when the body
  is in an unrecognizable state
• Teeth are composed of enamel, which resists
  decomposition. Comparison of x rays postmortem
  and perimortem
• 2. Characteristics of dental patterns and
  structure are unique like fingerprints. Also
  used for bite mark comparisons.

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Dental Images
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Forensic Engineering

• Study failures of engineering, accident
  reconstruction and the causes of fires and
  explosions, they investigate automobile
  accidents, material failure, and determine the
  cause of building collapse and structural
  failures.

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Forensic Computer Science

• Digital evidence the investigative use of
  computer technologies and electronic records.
• Finding hidden or deleted information. Tracing
  those who have committed computer crimes.
• Such as circulating child pornography or
  accessing unauthorized materials or confidential
  information

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• Recognition A crime scene specialist, with
  experience, learns to spot and recognize evidence
  that is important to the case.
• Classification to place things into groups
  according to their characteristics
• Individualization to demonstrate the object is
  unique, or that two separate objects were once
  one object.

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• Reconstruction the process of putting together
  the evidence available with an objective nature
  and create a sequence of events that created the
  evidence.