IT Service Management (ITSM) Best Practices for Advanced Computing
Forensic science%20from%20fingerprints%20to%20 dna
1. Pascal Goetgheluck/Science Photo Library
Forensic –
science from The forensic team
must collect as much
evidence as is
fingerprints
possible from the
crime scene.
to DNA
In the bedroom of 10 Main Street, Murrundrongo,
a man in his fifties lies dead on the floor next to
a bed . . . . . . with a broken glass bottle
nearby; reddish-brown stains on the
The man may have died of natural
causes, the stains could be from spilt
walls, a red stain on the carpet and red wine, and a cricket ball may have
the bathroom window smashed. smashed the bathroom window weeks
Roger Beckmann What’s been going on – accident or ago — or even after the death.
foul play? To put the pieces together, a team
This is the sort of puzzle that could effort is required. Police officers will
confront a crime scene investigator interview neighbours and gather
(CSI) from the police force. Crime information about the dead person.
scene investigators, often referred A doctor, or forensic pathologist, may
to as ‘scientific police’, are one part be called to examine the body. The
of the forensic team whose skills are police forensic team must look for
essential in modern police clues as to what occurred, and try to
investigation. In the fictitious scene reconstruct a possible sequence of
just described, police must determine events.
whether or not a crime has occurred.
2. The science of crime material using the observations,
measurements, physical evidence
Every day, many crimes are committed and photos collected by the CSIs.
in Australia. To solve these crimes They conduct:
effectively – so that criminals are • chemical analysis of paint, glass,
brought to justice – the police need to fibres, accelerants (substances
work very efficiently, using as many used to start a fire), explosives
techniques as possible. Science has (from discharged guns), inks and
become an essential tool for the printer toners;
modern police force. • biological analysis, which includes
Originally, the word ‘forensic’ meant analysis of DNA, body fluids,
anything relating to a law court. But fingerprints and swabs;
today it refers to a whole new subject. • document examination, which
Forensics or forensic science means involves examining hand-writing,
using science to solve crime. But what handwriting impressions (eg. from
exactly does a forensic scientist do? a note written on top of a pad
The work of a forensic scientist falls of paper), machine-generated
into three broad groups: field, documents, and paper and ink
laboratory and medical. types; and
Field workers or CSIs attend the • ballistics, which is the study of
scene of a suspected crime, record in firearms and ammunition, and the
detail what is present, and collect as identification of particular firearms
much evidence as possible – without from fired cartridge cases and
contaminating the scene in the bullets. Ballistics also involves
process. They search for marks left by calculating the direction and
AFP Forensic Services.
implements such as crowbars, knives distance that a bullet travelled.
or screwdrivers, or impressions from Another type of lab work in some
shoes and vehicle tyres. CSIs also police forces is toxicology. This means
investigate fires, explosions and illegal detecting and identifying drugs and
drug laboratories. poisons, and determining their effects
The lab-based forensic scientists on the body.
begin their painstaking analysis of
Science has become an
essential tool for the modern
police force. Analysis of objects determine if they
were used in a crime.
The third area of forensic science –
medical – is usually beyond the scope
of police teams. Specialists are
AFP Forensic Services.
brought in as required. Forensic
pathologists are most frequently used,
Searching for evidence that
may help solve the crime.
but there are also forensic dentists
(to identify teeth and bite marks) and
forensic psychiatrists. The medical
experts use their skills to gain
evidence about causes of injury and
death, or about the identity, behaviour
and motivation of a criminal.
Occasionally, other specialists may
be used. Botanists may be called
upon to identify pollen types found
on clothing, while engineers may give
advice on machinery, building
collapses or major fires. A recent
development in forensic science is
information technology, which means
using knowledge of computers and
software. As such, police will often
look for information on a suspect or
victim’s computer. New forms of crime
– so-called cybercrime – are making
use of computers as criminal tools, for
example to acquire information illegally
by ‘hacking’.
3. Four main uses of forensics determine which areas to concentrate Is it like the TV
their investigation on. For example,
In Australia, the police characterise four they may use luminol, which detects shows?
main uses of forensic investigation. traces of blood by reacting with the Forensic scientists are quick to point
These are: iron in the haemoglobin molecules out that TV dramas about their work
1. To prove an element of an offence, for that are within red blood cells. Luminol are inaccurate.
example, to identify a substance as glows when it comes into contact with The most common misconception
an illegal drug. blood. Sometimes it reveals small is that most forensic work is involved
2. To associate or disassociate a traces of blood that would normally with murders. Instead, it is involved
suspect from a crime scene or crime be invisible. with house burglaries, drug offences,
exhibit (for example, a weapon). The presence of blood, however, fires and vehicle accidents. Secondly,
does not mean it is from a human, or it is not the forensic experts’ job to
3. To help determine a possible, or even that it had anything to do with a
probable, sequence of events. confirm what police investigators would
crime. After all, people do occasionally like to hear. Forensic science, like any
4. To provide criminal intelligence, which cut themselves, which could leave form of science, involves having an
means to give extra information to the a tiny drop of blood on the carpet. open mind and being impartial.
police that may be used in the future. In the case of the smashed window The crime scene investigator or the
For example, if illegal drugs are at Number 10, the investigators lab scientist cannot afford to hang on
seized, careful analysis shows a discovered traces of blood on the to pet theories or preferred suspects.
chemical ‘signature’ which may reveal shards of glass, but the stains on He or she must work to uncover facts
what country or illegal laboratory the bedroom wall, and the liquid on that can be used as evidence. Quite
produced them. This may help with the carpet, were not from blood. often, these facts may serve to rule
other investigations. out many of the suspects that the
police have.
Finally, TV dramas tend to roll all
Meanwhile, back at 10 Main Street, forensic work into one person’s
the crime scene investigators will
thoroughly examine the area where the
Increasingly, responsibilities. In real life, forensic
scientists are specialists. No single
body was found. They will take detailed
notes and photographs, look for
CSIs are using person possesses all the knowledge
and expertise of every field of
fingerprints, palm prints and sole
prints; marks of tools and weapons; specialised forensics. Solving crimes is very much
teamwork, and modern teams are
marks from shoes; fibres from clothing
or material; fragments of paint and techniques large.
glass and body fluids.
Increasingly, CSIs are using
specialised techniques, on site, to
on site.
The cast of CSI (Crime Scene Investigation)
AFP Forensic Services.
WIN Television
Laboratory based forensic
employ a number of
accurate scientific
techniques.
4. WIN Television
Jorja Fox from
CSI, fires a gun
to compare
marks on the
bullet and shell.
Answers from the
dead
Pathology is the study of disease,
and cause of death. A forensic
pathologist specialises in examining
dead bodies to determine how and
Constantino Margiotta/Science Image Library.
when death occurred.
As well as examining the body, either
on site or through photos taken at the
scene, the forensic pathologist may
also use x-ray imaging and will usually
conduct an autopsy or post-mortem.
A post-mortem is a careful dissection
of the corpse, which comes from the
Latin language meaning after-death.
The pathologist will also take samples
of body tissues, like blood, liver or
hair, for further analysis.
The corpse may reveal what caused a person’s death.
One of the first tasks with a body evidence, linking a suspect to the
on site is to establish the time of crime. The remnants of explosive
death. The pathologist starts with material from a gunshot may also be
temperature. The normal temperature
o
present on the skin, for example, near
inside a human body is 37 C. a bullet hole. Such residues, and
A pathologist will take the temperature the bullet wound itself, can give
inside the body, as well as the information about the type of bullet
temperature in the place where the used, as well as the distance and
body was found. The rate at which direction from which it was fired.
body temperature falls after death At the autopsy, pathologists start
depends on the external temperature, with carefully looking at the body and
the clothing worn, the size of the body, its clothing. They then examine the
and its percentage of fat. skin — looking for cuts, scratches,
After 12 hours, most dead bodies stabs, wounds or injection needle
are the same temperature as their marks — and the nails.
surroundings, therefore other methods The body found at Number 10 had
are required for determining the time a long thin scratch on the shin of the
of death. There are many gradual right leg, and had been dead for about
changes that take place after death. eight hours before police arrived in the
These occur in a particular sequence, morning.
concluding with total decomposition.
Skilled pathologists can usually use
these changes to assess, roughly,
Secrets from within
when death occurred. Although a body does not always
After the dead body has been show marks on the outside, there is
examined at the scene, it is wrapped often evidence inside that will be
for transport. This is done very revealed during the autopsy. In our
carefully because small details — like scenario, the pathologist found the
fragments of skin, hair or blood caught back of the man’s skull cracked,
under a victim’s fingernails during a and a pool of blood inside the skull.
struggle — may provide crucial
5. An escape of blood from the blood
vessels like this is called a
haemorrhage. This type of internal
bleeding can be fatal, as the pressure
of the leaked blood damages the
brain.
There are other clues within a body
that can show up during an autopsy.
For example, a large blood clot within
a major artery or vein, or even in the
heart itself, may be a cause of natural
death, which would rule out foul play.
Samples of a person’s stomach
contents can reveal the last food
eaten. Blood analysis will show the
existence of any poisons, illegal drugs
or medicines. Urine in the bladder may AFP Forensic Services.
also be analysed.
Analysis of the blood from the body
found at 10 Main Street showed a high
concentration of alcohol. Stomach
analysis revealed the remains of red
wine and spirits. Also, damage to the
liver was a telltale sign that the DNA fingerprinting has become a powerful tool in helping solve crime.
deceased had been a heavy drinker
of alcohol. New prints are taken by a laser- DNA analysis does not enable
scanning procedure, where the hand scientists to build up a picture of
Print precision is placed on a flat glass plate, and its a person from their DNA. The only
print is stored and compared to other characteristic that the DNA tells us is
Analysis of fingerprints is probably the prints electronically. the sex of the person. DNA profiling is
most well known use of forensic A new form of identification relies only used to compare different DNA
science. Each fingertip has a pattern on DNA, which carries the genetic samples, and to determine whether or
of fine skin ridges that are slightly information of each person. Everyone’s not they could be from the same
different for every person — even DNA is different (except for identical person.
identical twins. twins). DNA profiling or typing is
sometimes called DNA fingerprinting
because it allows police to identify
Putting it all
an individual in the same way as together
fingerprints do. DNA can be extracted In our investigation of Number 10,
from any body fluid (blood, saliva, blood found on a shard of glass from
sweat, nasal mucus etc) or from the broken window yielded DNA
fragments of a body (hair roots, identical to the dead man. The scratch
torn skin or flesh). on his shin was recent, and probably
Forensic scientists do not look the source of the blood on the glass.
at the whole of a person’s DNA The sticky red liquid on the carpet
sequence, but rather a sub-set — a was found to be port wine, some of
DNA profile. DNA profiles are a very which was also found on the broken
powerful means of determining bottle. The source of the wall stains
whether two or more samples may or could not be determined, but they were
Everyone has a unique set of fingerprints. may not have come from the same not caused by blood.
person. If DNA profiles do not match, Police interviewed neighbours
they came from different people. separately, and their statements
A fingerprint is composed of grease However, if they do match, there is confirmed that the man, a heavy
and dried sweat left behind by the tips still a very slight chance that they drinker, often arrived home late at
of the fingers. The palms of the hand may have come from different people. night and had difficulty finding (and
also leave identifiable prints, as do the DNA is the same in every cell of the using) his keys. Sometimes he even
soles of the feet. body, and stays the same throughout tried to bang down his own door,
Fingerprints can be detected on a life. As such, DNA profiles taken at or else fall asleep in the bushes.
vast range of different surfaces using different times and places can be On the night he died, someone had
a variety of techniques. The police compared in order to determine heard his drunken singing. It was
keep a huge national database of whether or not they come from the probable that he broke the window to
prints taken from charged criminals. same person. gain entry to his own house, as it was
too cold a night to stay outside. The
DNA analysis does not enable forensic evidence suggested that,
while drunk, he fell onto a metal
radiator near his bed and died from
scientists to build up a picture the blow to his head. The bottle that
he was holding, broke as a result of
of a person from their DNA. his fall.
6. AFP Forensic Services.
Counting crime
Across Australia, the following crimes
were recorded in 2000:
approximately 227,000 residential
burglaries;
139,094 motor vehicle thefts;
15,630 sexual assaults;
9 474 armed robberies; and
342 murders.
It is important to realise that these
figures show recorded crime. Many
minor crimes and some serious crimes
are not reported to, or discovered, by
the police.
To establish the extent of crime in a
community, figures are often expressed
as rates per 100,000 people. This
shows that in Australia last year there
were just under 2 murders per 100,000
people.
It’s interesting to compare Australia’s
murder rate with other countries:
Brazil 10 per 100,000
USA 7 per 100,000 Everywhere we go,
we leave a telltale
Switzerland 3 per 100,000 sign of our presence.
Japan 1 per 100,000
These comparisons may be slightly It is almost The perfect crime?
inaccurate because of differences in the There are many examples of unsolved
way crime statistics are collected and
used around the world.
impossible to and undetected crimes, especially from
the past when forensic techniques
Even within a country, different areas be in a place were less sophisticated. Even today,
experience different crime rates. there are still crimes committed where
Therefore, figures can give a misleading without the criminal is not discovered.
picture of your likelihood of being a More often, however, forensic
victim of crime. What is clear, however, leaving a evidence allows police to link a
is that in Australia, violent crime is far suspect to a crime without enough
less common than theft. trace of your certainty to convince a court, and so
the suspect is not found guilty. If there
presence. are no other suspects connected to
the crime, the police must look for
more evidence – for example, from
later witnesses.
Correlation is not proof However, many criminals are
unaware of just how readily they can
As in all areas of science, evidence at the scene, may belong to someone be linked to a crime by the skilled use
from forensic investigation does not else. There are a number of of modern forensic techniques. It is
mean proof. A correlation between two possibilities. The suspect may have: almost impossible to be in a place
things does not mean that one causes • committed the murder; without leaving a trace of your
the other. • been present at the crime, presence in the form of a hair,
For example, you might observe that without committing the offence; discarded skin cells, clothing fibres
most people involved in car crashes • been present at the scene or traces of saliva.
wear seat belts, but this doesn’t mean innocently or suspiciously before
that seat belts cause crashes. Your the crime occurred;
observation is correct, but you cannot • arrived after the crime and left in
use it as evidence for the cause of fright; or,
accidents. You need to make further • been nowhere near the scene and
observations – for example, of people his jacket was used by someone
in cars who are not involved in else with or without his knowledge. The author would like to thank the
crashes. Australian Federal Police Forensic
Pieces of evidence may not always Therefore, all evidence must be Services, in particular Mr Karl Kent, for
agree. A fibre found at a murder scene taken together. Very rarely is one piece generous assistance with this article.
may match a male suspect’s jacket, of evidence conclusive proof.
but other evidence, such as DNA found