Download Introduction to Forensic Science and the Law

Chapter 1
Introduction
to Forensic Science
and the Law
“In school, every period ends with a bell. Every
sentence ends with a period. Every crime ends
with a sentence.”
—Stephen Wright, comedian
Introduction
Students will learn:
 How a crime lab works
 The growth and development of
forensic science through history
 Federal rules of evidence,
including the Frye standard and
the Daubert ruling
 Basic types of law in the
criminal justice system
Students will be able to:
 Describe how the scientific
method is used to solve forensic
problems
 Describe different jobs done by
forensic scientists and the
experts they consult.
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Forensic Science
 The study and application of science to matters
of law.
 Includes the business of providing timely,
accurate, and thorough information to all levels of
decision makers in our criminal justice system.
 The word forensic is derived from the Latin “forensis”
meaning forum, a public place where, in Roman
times, senators and others debated and held judicial
proceedings.
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Criminalistics vs Criminology
Criminalistics
Criminology
 the scientific
examination of
physical evidence
for legal purposes.
 includes the
psychological angle,
studying the crime
scene for motive,
traits, and behavior
that will help to
interpret the
evidence
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Specialized Duties
 Forensic Scientists – identify and/or compare
physical evidence through chemical, physical, and
instrumental analysis
 Criminologists – study criminal and behavioral
psychology to aid in criminal investigations
 Crime Scene Investigators – collect and preserve
physical evidence from crime scenes
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Specialized Duties
 Medical Examiners – perform autopsies to identify
the causes and manners of death
 Coroners – typically transport corpses from the crime
scene to the morgue; some aid in death investigations
 Prosecutors – initiate arrests, indictments and
prosecution of criminals
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Employment Qualifications
 Forensic Scientists – Bachelor of Science (BS) or higher in natural or
physical science
 Criminologists – BS or higher in sociology or psychology
 Crime Scene Investigators – law enforcement officers with a
certification, such as one from the International Association for Identification
(IAI)
 Medical Examiners (ME) – licensed pathologists possessing a Doctor
of Medicine (MD), that have completed several years of internship in pathology
 Coroners – equivalent to MEs in some jurisdictions; some are elected county
officials who handle corpse and death investigation
 Prosecutors – Doctor of Jurisprudence (JD) in criminal law
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Disciplines
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Trace Evidence (hair, fiber, paint, glass, impressions, etc.)
Latent Prints (fingerprints)
Forensic Biology (Serology/DNA)
Toxicology (blood alcohol, poisons)
Controlled substance (drugs)
Questioned documents (handwriting & typescripts)
Firearms (firearms and ammunition)
Others
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Crime Lab—Basic Services
 Physical Science Unit
 Chemistry
 Physics
 Geology
 Biology Unit
 Firearms Unit
 Document Examination
Unit
 Photography Unit
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Crime Lab—Optional Services
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Toxicology Unit
Latent Fingerprint Unit
Polygraph Unit
Voiceprint Analysis Unit
Evidence Collection Unit
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Employment Opportunities
 Federal Bureau of Investigation (FBI)
 Federal, State, and Local Crime Laboratories
 Drug Enforcement Administration (DEA)
 Bureau of Alcohol, Tobacco, Firearms, and
Explosives (ATF)
 U.S. Postal Service (USPS)
 U.S. Secret Service
 Central Intelligence Agency (CIA)
 U.S. Fish & Wildlife Services
 Teaching at community colleges and universities
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Other Forensic Science Services
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Forensic Pathology
Forensic Anthropology
Forensic Entomology
Forensic Psychiatry
Forensic Odontology
Forensic Engineering
Cybertechnology
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Montgomery County Crime Lab
 Facts and Figures:
*The crime lab has eleven sworn peace officers
*Crime lab personnel received 1,500 hours of training in 2014.
Some of the courses taken were:
-Basic Skeletal death investigation
-Advanced skeletal death investigation
-Advanced ridgeology
-Basic & Advanced Bloodstain analysis
-Bureau of ATF-Post Blast Investigation Training
-Latent print photography
-Basic, Intermediate, and Advanced Latent Print Analysis / Crime
Scene Reconstruction 1 & 2 / Basic and Advanced Shooting
Reconstruction
MC Crime Lab
*The crime scene investigators of the MCSO crime lab are all members
of the Texas Division of the International Association for Identification
(TDIAI).
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Crime Lab History
 First police crime lab in the world was established in
France in 1910 by Edmond Locard
 First police crime lab in the U.S. opened in 1923 in
Los Angeles
 The Scientific Crime Detection Lab was founded in
Evanston, Illinois in 1929
 The first FBI crime lab opened in 1932
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Major Developments
in Forensic Science History
 700s AD—Chinese used fingerprints to establish identity of documents
and clay sculptures
 ~1000—Roman courts determined that bloody palm prints were used
to frame a man in his brother’s murder
 1149—King Richard of England introduced the idea of the coroner to
investigate questionable death
 1200s—A murder in China is solved when flies were attracted to
invisible blood residue on a sword of a man in the community
 1598—Fidelus was first to practice forensic medicine in Italy
 1670—Anton Van Leeuwenhoek constructed the first high-powered
microscope
 1776—Paul Revere identified the body of General Joseph Warren
based on the false teeth he had made for him
 1784—John Toms convicted of murder on basis of torn edge of wad of
paper in pistol matching a piece of paper in his pocket
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Major Developments in Forensic
Science History
 1859—Gustav Kirchhoff and Robert Bunsen developed the science of
spectroscopy.
 1864—Crime scene photography developed
 1879—Alphonse Bertillon developed a system to identify people using
particular body measurements
 1896—Edward Henry developed first classification system for
fingerprint identification
 1900—Karl Landsteiner identified human blood groups
 1904—Edmond Locard formulated his famous principle, “Every contact
leaves a trace.”
 1922—Francis Aston developed the mass spectrometer.
 1959—James Watson and Francis Crick discover the DNA double helix
 1977—AFIS developed by FBI, fully automated in 1996
 1984—Jeffreys developed and used first DNA tests to be applied to a
criminal case
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1987
1996
1999
2001
2007
2008
2011
2011
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DNA catches the criminal
Tommy Lee Andrews convicted of a series of sexual assaults, using DNA
profiling.
DNA evidence certified
National Academy of Sciences announces DNA evidence is reliable.
Faster fingerprint IDs
FBI establishes the integrated automated fingerprint identification system,
cutting down fingerprint inquiry response from two weeks to two hours.
Faster DNA IDs
Technology speeds up DNA profiling time, from 6-8 weeks to between 1-2
days.
Footwear detection system
Britain's Forensic Science Service develops online footwear coding and
detection system. This helps police to identify footwear marks quickly.
Detection after cleaning
A way for scientists to visualize fingerprints even after the print has been
removed is developed, relating to how fingerprints can corrode metal surfaces.
Facial sketches matched to photos
Michigan state university develops software that automatically matches handdrawn facial sketches to mug shots stored in databases.
4 second dental match
Japanese researchers develop a dental x-ray matching system. This system
can automatically match dental x-rays in a database, and makes a positive
match in less than 4 seconds.
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People of Historical Significance
Edmond Locard (1877-1966)
 French professor
 Considered the father of
criminalistics
 Built the world’s first forensic
laboratory in France in 1910
 Locard Exchange Principle
 Whenever two objects come into
contact with each other, traces of each
are exchanged.
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Crime Scene Team
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A group of professional investigators, each trained in a variety of special
disciplines.
Team Members
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First Police Officer on the scene
Medics (if necessary)
Investigator(s)
Medical Examiner or Representative (if necessary)
Photographer and/or Field Evidence Technician
Lab Experts
pathologist
serologist
DNA expert
toxicologist
forensic odontologist
forensic anthropologist
forensic psychologist
forensic entomologist
firearm examiner
bomb and arson expert
document and handwriting experts fingerprint expert
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MC Mobile Crime Lab
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Scientific Method
(as it pertains to criminalistics)
1. Observe a problem or questioned evidence
and collect objective data.
2. Consider a hypothesis or possible solution.
3. Examine, test, and then analyze the
evidence.
4. Determine the significance of the evidence.
5. Formulate a theory based on evaluation of
the significance of the evidence
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Complex Reasoning Skills
Necessary to Work Through and Solve Crimes:
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Deductive and Inductive Reasoning
Classifying
Comparing and Contrasting
Problem Solving
Analyzing Perspectives
Constructing Support
Error Analysis
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Laws that Pertain to the
U.S. Criminal Justice System
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The U.S. Constitution
Statutory Law
Common Law or Case Law
Civil Law
Criminal Law
Equity Law
Administrative Law
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The Bill of Rights
Gives individuals the right:
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To be presumed innocent until
proven guilty
Not to be searched unreasonably
Not to be arrested without probable
cause
Against unreasonable seizure of
personal property
Against self-incrimination
To fair questioning by police
To protection from physical harm
throughout the justice process
To an attorney
To trial by jury
To know any charges against
oneself
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To cross-examine prosecution
witnesses
To speak and present witnesses
Not to be tried again for the same
crime
Against cruel and unusual
punishment
To due process
To a speedy trial
Against excessive bail
Against excessive fines
To be treated the same as others,
regardless of race, gender, religious
preference, country of origin, and
other personal attributes
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Miranda v Arizona
 In 1963, Ernesto Miranda, a 23 year old mentally
disturbed man, was accused of kidnapping and
raping an 18-year-old woman in Phoenix, Arizona. He
was brought in for questioning, and confessed to the
crime. He was not told that he did not have to speak
or that he could have a lawyer present. At trial,
Miranda's lawyer tried to get the confession thrown
out, but the motion was denied. The case went to the
Supreme Court in 1966. The Court ruled that the
statements made to the police could not be used as
evidence, since Mr. Miranda had not been advised of
his rights. The real story
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Miranda Rights
The following is a minimal Miranda
warning:
 You have the right to remain silent. Anything
you say can and will be used against you in
a court of law. You have the right to speak to
an attorney, and to have an attorney present
during any questioning. If you cannot afford
a lawyer, one will be provided for you at the
government’s expense.
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Evidence Collection –
The Fourth Amendment
 Right of Search and Seizure Regulated
 “The right of the people to be secure in their
persons, houses, papers, and effects, against
unreasonable searches and seizures, shall not be
violated, and no warrants shall issue, but upon
probable cause, supported by oath or affirmation,
and particularly describing the place to be
searched, and the persons or things to be seized.”
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Evidence Collection –
The Fourth Amendment (continued)
Unlawful Search and Seizure
 When the court says an individual’s rights
were violated, any evidence derived from
the search and seizure will be kept out of
the criminal case, if the case is against the
person whose rights were violated
 It is very important that evidence is
collected lawfully, without an evasion of
privacy or with a search warrant, so it will
not be ruled inadmissible in court
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Evidence Collection –
The Fourth Amendment (continued)
 Searching – Was There an Invasion of
Privacy? The court will ask two things (if
either of these answers is no, then any
evidence collected can be admissible in
court)
 Did the owner of the home or property that
was investigated or searched expect a
“degree of privacy”?
 Was this expectation of privacy reasonable
and legitimate?
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Evidence Collection –
The Fourth Amendment (continued)
Search Warrant – a judicial order that
authorizes the law enforcement agencies
to conduct a search of a location/person
and to seize any evidence of a criminal
offense. To issue a search warrant police
have to show the judge that
 Probable cause exists that a crime has
occurred
 Evidence or contraband linked to the crime
will probably be found on a certain location on
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Evidence Collection –
The Fourth Amendment (continued)
 Search Warrant Not Needed
 Consent is given for the search (no warrant is
needed, even in the future, once consent is
given)
 Emergency – someone is in danger, or there
might be destruction of evidence
 After an arrest – an officer can search the
person and immediate surroundings
 Plain view – if the police are there legally and
evidence is in plain view
 Reasonable suspicion – if police believe they
will find a weapon or drugs on a person or in a
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car, they can legally search
Regulations for the Prosecution –
Fifth Amendment
 “No person shall be held to answer for a capital, or
otherwise infamous crime, unless on an indictment
of a Grand Jury, except in cases arising in the land
or naval forces, or in the militia, when in actual
service in time of war or public danger; nor shall
any person be subject for the same offense to be
twice put in jeopardy of life or limb; nor shall be
compelled in any criminal case to be a witness
against himself, nor be deprived of life, liberty, or
property, without due process of law; nor shall
private property be taken for public use without just
compensation.”
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Regulations for the Prosecution –
Fifth Amendment (continued)
 Difficult/Publicized/Capitol Cases
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In many states, a grand jury (16 – 24 citizens)
meets to decide if there is enough evidence before
a citizen can even be indicted for a crime
The grand jury is an “arm” of the prosecutor office,
the defense does not even present at a grand jury
 Double Jeopardy
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It is imperative that every bit of evidence be found
in the case before it is brought to trial
If a person is found innocent of a crime and more
evidence is discovered after the trial, the person
cannot be put on trial again for that same crime
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Regulations for the Prosecution –
Fifth Amendment (continued)
Due Process – everyone is treated the
same
Plea Bargaining – even with all the hard
work and effort put forth by law
enforcement officials toward criminal
cases, up to 90% of all cases are plea
bargained and never go to trial (Deslich,
2006)
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Trial Policies –
Sixth Amendment
 “In all criminal prosecutions, the accused shall
enjoy the right to a speedy and public trial, by
an impartial jury of the state and district
wherein the crime shall have been committed,
which district shall have been previously
ascertained by law, and to be informed of the
nature and cause of the accusation; to be
confronted with the witnesses against him; to
have compulsory process for obtaining
witnesses in his favor, and to have the
assistance of counsel for his defense.”
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Trial Policies –
Sixth Amendment (continued)
 Speedy Trial
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Depends on state statute, but generally 90 – 120 days for an
imprisoned defendant, unless waived by the individual
The following slow the process:
 The defendant is out on bail
 Motions
 Illness
 Lack of attorney(s)
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The defendant can ask for a speedier trial; for law
enforcement this is mixed news
 Speedy trial rules make it imperative to find all of the evidence
as soon as possible
 Delays might be beneficial to law enforcement because they
lengthen the evidence collection and analysis time period
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Trial Policies –
Sixth Amendment (continued)
 Witnesses – any witness for the defense or the
prosecution can be subpoenaed to appear in
court
 Informed of Charge
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Once arrested, a defendant has 72 hours to be
arraigned, told what he is charged with, and offer
his plea
The more evidence collected before the arrest
 The better it is known
 What to charge the defendant with
 The extent of the charges
 Has implications regarding the amount of the bail
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Trial Policies –
Sixth Amendment (continued)
 Defense Council
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A defendant has the right to an attorney
If they can’t afford one, the court must provide one
A defense attorney must know every bit of the
prosecutor’s evidence in the case to prepare
The defense attorney’s job is to get the defendant
freed—any and all evidence and evidence
procedures can be questioned; this includes
collection, handling, delivery, analysis, testimony,
and documentation
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Trial Policies –
Seventh Amendment
“In suits at common law, where the
value in controversy shall exceed
twenty dollars, the right of trial by jury
shall be preserved, and no fact tried by
a jury shall be otherwise reexamined in
any court of the United States, than
according to the rules of the common
law.”
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Trial Policies –
Seventh Amendment (continued)
 Impartial Trial by Jury
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Jury of the individual’s peers is the standard
Some evidence and its analysis are very intricate,
detailed, and difficult to understand outside of the
scientific community; this can help or hurt the
defendant
 United States Court – all courts used for trials
should be controlled by the United States
government; furthermore, all verdicts handed
down by these courts are final (unless
appealed to a higher court)
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The Evidence in Court
 How evidence is received in a court of law is
extremely important to a crime scene
professional
 Because of the Constitution’s view of “innocent
until proven guilty” and the rights of the
accused, it is crucial that those in law
enforcement understand the types of evidence,
how it is perceived in court, how to testify to its
significance, and the importance of proper
evidence collection and handling
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Power of the Evidence in Court
 Probative Value
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Higher value if the evidence can prove something in
court
The lower the probability of an event, the higher the
probative value
 Probability – the frequency of the occurrence of
an event
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Defines the odds that a certain event will occur (or the
matching of a certain pieces of evidence)
Normally found by multiplying the odds
Example – if a coin is flipped 100 times and comes up
heads 50 times, the probability of coming up heads is
50 out of 100, or 5 out of 10
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Power of the Evidence in Court
(continued)
 Product Rule – calculate the overall frequency of
occurrence of in a population
•
Example – the OJ Simpson case: Blood factors from a crime scene that match OJ’s
blood (Bertino, 2009)
Blood
Factors
A
EsD
PGM 2+2•
•
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Frequency Decimal of
in
the
Population Frequency
(%)
26%
.26
85%
.85
2%
.02
Product Rule – 26 x .85 x .02 = .0044 or 0.44%, or less than 1 out of 200 people would
be expected to have this combination of blood factors
Chart explained
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Types of Evidence in Court
Direct Evidence – evidence that
establishes a fact
 Eyewitness
testimony or victim’s testimony
 Confessions
 Physical evidence found on a person
 Audio or visual recording of the act or
crime
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Types of Evidence in Court (continued)
 Indirect Evidence
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Circumstantial evidence
 Requires that a judge and/or jury make inferences about
what transpired at the scene of a crime
 Not definitive proof
 Physical evidence is nearly always circumstantial, so
evidence analyzed forensically is mostly circumstantial
evidence
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Inference example – fingerprints or hairs found at
the scene are consistent with that of a perpetrator;
jurors may infer that the print or hair belongs to the
defendant after this evidence is presented, linking
the defendant to the scene
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Influence of Direct
vs. Indirect Evidence
 Circumstantial evidence is more objective,
while direct evidence is subjective
 In general, direct evidence is not considered to
be as reliable as circumstantial evidence
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Eyewitnesses can be deficient when identifying
perpetrators or remembering certain events
Flawed questioning techniques can lead to
erroneous testimony and confessions
The age of the eyewitness and the passing of time
since the event can also lead to faulty testimony
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Influence of Direct
vs. Indirect Evidence (continued)
 Court research comparing the impact of
the type of evidence differs in its results
Some research says direct (eyewitness)
evidence has a stronger impact on the jury
 At other times, physical evidence was
considered more valid by jurors
 Some studies suggest that having both types
of evidence is no more compelling than having
strong evidence of only one type
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Influence of Direct
vs. Indirect Evidence (continued)
 The forensic scientist should
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Always be aware of the persuasive nature of
eyewitness testimony
In no way allow that to interfere with the scientific
method when
Analyze physical evidence
Develop a hypothesis when investigating a crime
 The direct evidence of a police officer’s testimony
(concerning the source of evidence,
documentation, and chain of custody) corroborates
and strengthens the probative value of physical
evidence
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Categories of Physical Evidence
Individual Evidence – evidence that can
be linked to a unique, specific source
with a very high degree of probability
 Examples
Matching ridge characteristics of fingerprints
Matching striations of two different bullets from
the same gun
The irregular edges of a broken object (paper,
glass, etc.) that fit together like a jigsaw puzzle
(this type of evidence is not found very often)
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Categories of Physical Evidence
(continued)
Class Evidence – evidence that can
only be associated with a group and
never a single source
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way to increase the probative value of
class evidence is to find as many different
types of class evidence as possible to link
the suspect to the crime
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Evidence Admissibility
In a Court of Law
 Not only will the court compare the Bill of
Rights to how evidence was collected, but
there are court precedents that determine
the admissibility of scientific results and
how those results are explained in court
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Frye v. United States, 1923 – The Frye
Standard: the questioned scientific procedure
or principles must be “generally accepted” by
a majority of the scientific community
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Evidence Admissibility
In a Court of Law (continued)
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Daughbert v. Merrell Dow Pharmaceuticals,
1993
 Verdict replaced the Frye Standard
 Areas of inquiry by the judge acting as the gatekeeper
 Can the scientific technique or theory be tested?
 Has the technique or theory been subjected to peer
review?
 What is the technique’s potential rate of error?
 Are there standards to control the technique’s
operation, and are these maintained?
 Has the technique or theory attracted widespread
acceptance within scientific community?
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Admissibility of Evidence
1923 Frye v. United States
1993 Daubert v. Dow
 Scientific evidence is allowed
into the courtroom if it is
generally accepted by the
relevant scientific community.
The Frye standard does not
offer any guidance on reliability.
The evidence is presented in
the trial and the jury decides if it
can be used.
Admissibility is determined by:
 Whether the theory or
technique can be tested
 Whether the science has been
offered for peer review
 Whether the rate of error is
acceptable
 Whether the method at issue
enjoys widespread acceptance.
 Whether the opinion is relevant
to the issue
The judge decides if the evidence
can be entered into the trial.
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Federal Rules of
Evidence Expert Testimony
 Expert Testimony – hearsay from a witness is
normally not allowed in court, except in the case of
an expert witness
 Expert Witness – a witness “qualified as an expert
by knowledge, skill, experience, training, or
education” (Deslich, 2006) may offer expert
testimony on a scientific matter if
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The testimony is based upon sufficient facts
The testimony is the product of reliable principles and
methods
The witness has applied the principles and methods
reliably to the facts of the case
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Court Significance of Procedures in
Evidence Collection and Analysis
 Every step of the process for collecting,
handling, analyzing, transporting, and
storing evidence is scrutinized in a court of
law. So there are guidelines that must be
followed for forensic evidence and its
results to be admissible in court
A systemic search for all evidence must be
conducted
 All evidence must be collected, including large
items and trace evidence that must be
vacuumed
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Court Significance of Procedures in
Evidence Collection and Analysis
(continued)
 Comparison-type evidence should be
collected when possible
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Reference Samples – should be collected for
comparison
Examples
 Paint chip from a hit-and-run suspect
 Blood and hair samples from the victim, suspects, all
family members (and pets), and crime scene
investigators
 These reference samples are then available for
comparison, elimination, and matching to those
unknown specimens collected at the crime scene
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Court Significance of Procedures in
Evidence Collection and Analysis
(continued)
 Proper packaging and separation of evidence is
crucial
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Cross-contamination (or contact) with other
persons or evidence is to be avoided at all cost
Proper tools for collection and storage should
always be used (envelopes, vials, bags, etc.)
Always follow strict packaging guidelines for all
evidence, and never package any two pieces of
evidence together
Decontamination of personnel between crime
scenes is important
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Court Significance of Procedures in
Evidence Collection and Analysis
(continued)
 Chain of Custody – the witnessed, written record of
all individuals who had the evidence in their
possession from the crime scene to the courtroom;
and when, where, and for what purpose this transfer
of evidence occurred
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
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The item of evidence itself should be identified; the location,
time, and person collecting should also be recorded
The evidence container should also be marked for
identification, showing the collector’s initials, the location of
evidence, and the date it was received by the collector
If the evidence is turned over to another individual for any
reason (care or delivery), this transfer must be recorded in
the notes and/or forms
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Court Significance of Procedures in
Evidence Collection and Analysis
(continued)
 Chain of Custody (continued)
Any samples of the evidence taken for testing
or any changes in the evidence should be
documented immediately
 Every individual who possesses the evidence
must maintain a written record of its
acquisition/disposition and may be called to
testify in court; this includes individuals from
the collection, to delivery, to the laboratory
analysis, and then into the courtroom with the
prosecuting attorney
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Court Significance of Procedures in
Evidence Collection and Analysis
(continued)
 Chain of Custody (continued)
To avoid confusion, the number of individuals
involved in the chain of custody, should be
kept to a minimum
 The chain of custody record is often kept as a
form on the container or envelope of the
evidence
 Failure to substantiate the evidence’s chain of
custody may lead to serious questions
regarding the authenticity and integrity of the
evidence
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Types of Crimes
 Infraction
 Misdemeanor
 Felony
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Federal Rules of Evidence
In order for evidence
to be admissible, it
must be:
 Probative—actually
prove something
 Material—address an
issue that is relevant to
the particular crime
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Facets of Guilt
Try to prove:


Means—person had the ability to do the crime
Motive—person had a reason to do the crime
(not necessary to prove in a court of law)

Opportunity—person can be placed at the
crime
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“If the Law has made you a witness, remain a
man (woman) of science.
You have no victim to avenge, no guilty or
innocent person to ruin or save.
You must bear testimony within the limits of
science.”
—P.C.H. Brouardel
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