Forensic Science:A Brief Introduction to the Disciplines
November 2015
Jane Austin
(Any errors in this presentation are all mine)
Today’s Session
• Historical Context
• Overview of Forensic
Science Disciplines
• How they are used in
crime investigations
Historical Context
• Forensic Science dates back to 12thC… gathered
momentum in 17thC
• The word forensic comes from the Latin, forēnsis, meaning
"of or before the forum."
• Term originates from Roman times (a criminal charge was
presented to a group of public individuals in the forum).
• Autopsy - from Greek, from autoptēs ‘eyewitness’, from
autos ‘self’ + optos ‘seen’ – to see for oneself
• Recently, made popular in books and Tv series such as CSI,
NCIS, Silent Witness
UK
Sir Bernard Spilsbury
1877-1944
• Studied at St Mary’s Hospital,
Paddington in 1899.
• Specialised in emerging science of
FORENSIC PATHOLOGY
• First and most famous case was
the trial of Hawley Harvey Crippen
(“Dr Crippen”)
Dr Crippen
• Provided forensic evidence that the
victim found in Crippen's house was
Mrs Cora Crippen
• Based on a scar on a small piece of
skin from the remains.
• But…….
• Spilbury's authoritarian approach and his
unnerving self-belief gave rise to criticism
among judiciary
• Recent research has shown that some of his
conclusions led to miscarriages of justice
• That said, in 2008, files containing Spilsbury’s
detailed notes on deaths (from 1905-1932) went
to Sotheby's and were acquired by the
Wellcome Library, London.
Spilsbury’s Cases
Wellcome Trust
• Biomedical research charity, established 1936, to fund biomedical research, support public understanding of science, and improve human and animal health.
• UK’s largest provider of non-governmental funding for scientific research and one of the largest providers in the world.
• In medical research, it is world's second-largest private funder after Bill & Melinda Gates Foundation (ref. FT)
Well worth a visit!
Wellcome Trust
USA - Frances Glessner Lee (1878-1962)
• In 1936 inherited the family fortune. Developed a passion
for forensics, inspired by her brother’s friend, Magrath,
who was Boston’s medical examiner
• Wanted to reform the country’s legal medicine system.
• Donated money to Harvard to create a Chair for Legal
Medicine and GB Magrath Library of Legal Medicine
• Established the first US forensic pathology program
• Most remembered for her dioramas of crime scenes
• “The Nutshell Studies of Unexplained Death"
Dioramas of Crime Scenes
Dioramas of Crime Scenes
Forensic Disciplines
• Biology, Chemistry, Physics
• Anthropology
• Botany and Ecology
• Blood Pattern Analysis
• Dentistry
• Digital
• DNA Profiling
• Engineering
• Entomology
• Pathology
• Psychology
• And many more…..
Forensic Botany
Forensic Botany
Scientific study of plants, or the application of plant sciences to criminal investigations.
Incorporates a number of sub-disciplines:
• palynology (pollens)
• dendrochronology (tree rings)
• limnology (aquatic environments)
• systematics (the classification of plants)
• ecology (ecosystems), and
• molecular biology.
Forensic Botany
• Forensic botanists examine plant matter to
determine their species and origin.
• Suspects may leave behind plant parts, spores or
seeds adhered to their clothing.
• Some species found only in limited areas…. their
presence at the crime scene may indicate where
suspects have been or where they live/work.
• Forensic botanists also can be essential in locating
clandestine gardens or greenhouses used to
cultivate such illegal plants as marijuana.
Pollen
• Powder-like, abundant and easily
transported. Pollen grains are often
found on clothes, hair or skin.
• Can connect a suspect to a victim or
crime scene….
• If investigators find a rare plant type
near a murder victim, the presence of
its pollen on suspect could place them
at the scene. Images:
Rob Kesseler Madeline Harley
Pollen
• Even for common plants, each
environment has its own unique
combination of pollens; this 'signature'
can link an individual or object to a
location.
• Pollen signatures may also indicate that
a body has been moved or suggest the
type of area where the original crime
took place.Images:
Rob Kesseler Madeline Harley
Botany and
hidden graves
• When soil disturbed, certain plants quickly invade the fresh
surface.
• Other species follow in succession until the area recovers.
• But the new composition and distribution is never identical
to original plant community.
• Also, a buried body may chemically change the soil, and
may promote or inhibit growth - area will be different from
its surroundings.
• These differences may be visible for decades.
Botany and the
time since death
• Diatoms can be used to diagnose death by
drowning in freshwater.
• Botanists identify number and species of
diatoms present in lungs and other tissues,
correlate them with flora from location of body.
• Diatoms vary seasonally, and this can also help
in approximating time since death.
• Unique ‘Signature' of an aquatic habitat can
match a body to a given location
Botany and time since death
• Trees and roots are also useful for determining elapsed
time since death
• Woody plants and trees grow in annual cycles and the
growth rings can provide clues to the timing of an event,
sometimes centuries later.
Particularly accurate if roots grow
through clothing or bone. Even partial
damage to root growth can suggest the
period since the burial occurred.
Forensic Dentistry
Forensic Dentistry
Main areas of practice:
• Identification of human remains
• Identification in mass fatalities
• Assessment of bite mark injuries
• Assessment of cases of abuse (such as child,
spouse or abuse of the elderly)
• Age estimation, race, occupation, socio-
economic status
Blood Pattern Analysis (BPA)
Blood Pattern
Analysis
• The interpretation of bloodstains at a crime scene
in order to recreate the actions that caused the
bloodshed.
• Analyse size, shape, distribution and location of
bloodstains
• Form opinions about what did or did not happen.
Typical scene
Blood Pattern
Analysis
• Chemical considerations - red to brown as
oxy-haemoglobin changes to
methaemaglobin and haemichrome
• Physical considerations - fluid to solid,
effects of gravity, viscosity, surface tension
• Flight characteristics - angle of impact,
area of origin
Bloodstain Pattern
Analysis
Digital Forensics
Digital Forensics
• Digital Forensics is study of information stored or
transmitted in digital form that may be used in trial
• Before accepting digital evidence, a court
determines if evidence is relevant, authentic and
whether copy or original is acceptable.
• Need assurances regarding chain of custody
Digital Evidence
Use of digital evidence increased in last few
decades…. Many high profile cases in the press
Courts have allowed the use of range of evidence:
• Emails, digital photos, video and audio files
• Instant messaging histories
• ATM transaction Logs
• Accounting programs and spreadsheets
• WP documents
• Internet Histories, Database records
• Contents of computer memories
• GPS tracking/Mobile Records
• Logs for hotel electronic door locks
Defending a Digital Case
Common lines of defence are that:
• Trojan or 'pop-up' was responsible for presence of any illegal material on the defendant's computer.
• Such material was unsolicited and was 'pushed' to them via MSN, a peer to peer application such as Kazaa or email.
• It was one-time idle curiosity….
Prosecuting a Digital Case
Such “explanations” can be countered by proving that the
defendant had sought such material by:
• signing up to a service using a credit card
• searching within a peer-to-peer application
• entering keywords in an internet search engine
• sheer quantities of material and periods of exposure
For digital evidence to be admissible, a clear “chain of
custody” required, detailing who had access to digital
device & when, contemporaneous notes of all actions
taken, particularly in relation to the technical processes.
DNA Profiling
DNA Profiling
Developed from two independent breakthroughs in
molecular biology:
• In USA, the polymerase chain reaction (PCR) was
invented by Kary Mullis
• In UK, DNA fingerprinting was being discovered by
Professor Sir Alec Jeffreys at the University of
Leicester.
• Multi-locus probing (MLP) technique results in probes
binding to multiple DNA fragments, giving rise to
traditional 'bar-code' pattern.
DNA Short Tandem Repeats
• DNA profiling involves the testing of highly variable
regions of a person’s DNA that contain short repeating
sequences called STRs (short tandem repeats).
• Because we inherit DNA from both parents, DNA
profiles can be used to confirm if people are closely
related eg paternity, siblings
• STR very sensitive technique, requires only a small
quantity of DNA eg blood, semen, skin, saliva,
mucus, perspiration and the roots of hair
First Conviction using
DNA Profiling
Professor Jeffreys used DNA techniques to link semen
stain samples, collected from two rapes/murders that
occurred 3yrs apart (1983 & 1986), in a small
Leicestershire village.
• Semen was type found in only 10% of men, and was
from someone with Type A blood group.
• As a result, first mass DNA profile screening in the
world was undertaken in Leicester
• Blood and saliva samples from 4,000 men with no
alibi who lived in the local villages
But still no DNA match was found…….
• In August 1987, a woman overheard a colleague boasting
that he had given a sample for a friend, Colin Pitchfork.
• Police arrested Pitchfork in September 1987, and scientists
found that his DNA profile matched that of the murderer.
First Conviction…
In this first case, DNA profiling and screening was able to :
• Link the two crimes, several years apart
• Secure the conviction of the perpetrator
• Exonerate an innocent man.
Only one-in-a-billion chance that profiles are from
two different people, unless they are identical twins.
Forensic Entomology
Forensic Entomology
Involves the study of arthropods, including insects,
arachnids, centipedes, millipedes, and crustaceans in
criminal or legal cases … murder, suicide, rape,
physical abuse and contraband trafficking
Forensic
Entomology
• In murder investigations, the focus is on:
• which eggs (eg types of insects) are present
• their location on the body, and
• in what order they appear.
• This is helpful in determining Postmortem Interval
(PMI) and Location of death.
Hence, their presence
together with other
evidence can also point
to times and locations
where other events
may have occurred.
Many insects exhibit:
Endemism (occur only in certain places)
Phenology (active only in certain season, or time of day).
Forensic Entomology
Blow Flies
• Blow flies are first insects to come in contact with dead
body… great forensic importance
• Reputedly, they have the ability to “smell death” from 10
miles away.
• Blow flies (Calliphoridae) often metallic in appearance,
10 - 14 mm in length. Includes blue bottles; 1200 species
• Hatching from egg to first larval stage takes from 8hrs to
one day. Found in temperate to tropical areas….larvae
thrive and pupate in loose, damp litter.
Photo by:
L. West/Bruce Coleman Inc
Blowflies and Decay
• Duration of decay process depends on climatic
conditions & yearly temperature changes
• Corpses in summer and rainy season decay at
much faster rate than those in winter and spring.
• Lower temperatures slow down the development
of the larvae (maggots).
• Higher temperature of the corpse due to maggot
activity (core maggot mass) itself also speeds up
decay.
Forensic Psychology
• Forensic psychology is the intersection between psychology and the justice system.
• Includes clinical, social, organisational or any other branch of psychology….
• Important aspects of forensic psychologist’s work includes the ability to:
• testify in court as an EXPERT WITNESS
• discuss cases that involve issues with the brain or brain damage. They may also deal with issues of whether a person is legally competent to stand trial.
• assess the state of mind of the defendant at the time of the offence, and to provide an evaluation of the defendant's sanity or insanity (which relates to criminal responsibility) at the time of the offence.
• provide sentencing and treatment recommendations, or any other information the judge requests, such as information regarding mitigating factors, assessment of future risk and evaluation of witness credibility.
And finally…
Body Farms
Body farms
• A body farm is a research facility where
decomposition can be studied in a variety of
settings.
• Aim - to gain a better understanding of the
decomposition process, to develop techniques for
extracting information (such as the timing and
circumstances of death) from human remains
• Six such facilities exist in the United States.
• Largest facility is operated by Texas State
University (7 acres).
Thank you for listening