criminal investigation in Sri Lanka
DNA for justice
By Prof. S.K. Ballal and Suneth Sooriyapathirana
Sri Lanka's increasing crime rate has deeply upset
the peaceful lifestyle and economic development of the country.
The Department of Police and national system of justice are heavily
burdened and it is often debatable, whether the current investigating
methods are effective in meeting the backlog of cases.
profiling and DNA databases are commonly employed for criminal investigations
in developed countries. This is an improvement on the traditional
system of criminal investigations, especially in terms of accuracy
in decision making. It is suggested that this modern method be used
in Sri Lanka as well.
usual approach to investigation in criminal cases in Sri Lanka is
through eyewitnesses and conventional forensic investigations. The
most unfortunate mistake in a prosecution is imposing the death
penalty or long incarceration on an innocent person.The most common
cause of wrongful conviction is a mistaken testimony of an eyewitness.
Evidence of an eyewitness is "persuasive" evidence in
trials today.But memory is extremely plastic and unreliable even
when the victim attempts to carefully "remember" the faces
and events. Time lapse, stress, confusion and fear can lead to a
conventional approach of forensic investigation is another channel
of finding evidence. It includes post-mortems and biological evidence.
Most often in bomb blasts, bodies are reduced to small particles
and cannot be identified by conventional means.
is DNA ?
Modern forensic DNA profiling is rapidly changing all
facets of the criminal justice system because of the extreme sensitivity
and high levels of accuracy inherent in this method. Therefore,
it is necessary to understand the biological basis behind DNA profiling
and why it has been considered as the most accurate system of identifying
criminals in modern day police investigations.
of us is made up of hundreds of billions of cells and every individual
is derived from a single fertilized egg cell. Fertilization is the
union of male sperm (from the father) and female ovum (from the
mother). Our cells have an enormous amount of complexity in structural
arrangement with many parts inside. In the nucleus of the cells,
threadlike structures called chromosomes are found which carry the
genetic information called DNA that are essential for architecture,
maintenance and reproduction of our bodies.
DNA codes for genetic information define who we are and what makes
us individuals with unique traits.
Each one of us is different in hundreds of characters while sharing
many common features. This individuality exists because, each one
of us has a unique set of DNA except for identical twins.
All we need for investigation is a few cells of DNA .They
can be extracted from anything ranging from a spot of blood , semen,
hair, finger nail scrapings, to cigarette butts, and chewing gums.
Biological samples that are decades old, ravaged by fire and decayed
also can be used because DNA is relatively stable to drying, heat
first use of DNA profiling in a criminal investigation occurred
in 1986 in the United Kingdom and in same year, the US Federal Bureau
of Investigation (FBI) and the US commercial laboratories began
using DNA profiling methods. In Sri Lanka DNA profiling was used
to identify the suspects of the Hokandara mass murder and this technique
is popularized in Sri Lanka as DNA fingerprinting although there
is no "finger print" in a conventional sense.Now, it has
been clearly defined with the correct term, DNA profiling.
of the victims from the September 11, 2001, terrorist attacks on
the World Trade Center, New York has been the largest and most difficult
forensic DNA investigation in history because, in most bodies of
victims, tissue destruction was total.
profiles obtained from these human debris were compared with the
DNA profiles that were obtained from the personal items from the
victims’ houses - such as razor blades, combs, tooth brushes,
clothing and other items as well as about 7,000 check swabs from
the victims' relatives. By September 2002, about half of the World
Trade Center victims had been identified.
goal was the identification of all the victims by the middle of
2003, which has been accomplished. In July 1995, Serbian troops
seized the Bosnian town of Srebrenica. About 25,000 Muslim inhabitants
were attacked and over 7,500 people were shipped to execution sites,
killed and buried in mass graves. This massacre was the largest
mass murder since World War II. When DNA profiling was used, most
of the victims were identified by the end of 2002.
were similar incidents of mass graves in Sri Lanka at Sooriyakanda
and at Chemmini in Jaffna Thus, DNA profiling could be used to probe
these types of massacres.
of DNA profiling
1. Convicting the guilty and exonerating the innocent-
DNA profiles from rape, burglary and other crime scenes
can be matched with the suspects. Also, DNA profiles from multiple
crime scenes can be compared in order to identify common perpetrators.
Innocents could be exonerated. For example, in the US 123 innocent
people have had their convictions overturned using DNA evidence
alone. Twelve of these were death row inmates, some only days or
hours away from execution. Cases already filed and convicts already
punished can be re-examined if there is a suspicion that they were
Excluding suspects -
History shows that in sexual assault cases, DNA evidence
excluded about 25% of primary suspects prior to trial. This not
only allows police forces to redirect investigations at an early
stage but also saves resources and the injustice of bringing innocent
people to trial.
Identifying missing persons -
DNA profiles obtained from the remains of missing persons
can be compared with profiles from relatives in order to establish
the identity of body or skeletal remains.
Establishing paternity -
DNA evidence can help to establish parentage. A recent example of
DNA profiling in a paternity case was that of Thomas Jefferson,
the third president of the US. The DNA profiling revealed that Jefferson
could have fathered children by Sally Hemings, one of his slaves.
5. Identifying military personnel -
The military can obtain DNA samples from its personnel
so as to identify soldiers who may be killed in the line of duty.
Identifying disaster victims -
DNA profiling can be employed to identify victims of air
crashes, terrorist attacks and other catastrophes.
7. Identifying victims of mass murders and assassinations -
8. Identifying protected species (wild life forensics)
DNA in animals
DNA samples have been used to determine whether the remains of a
particular animal came from an endangered or protected species.
DNA profiles have linked animal remains with a crime scene or with
reliability of DNA profiling can be significantly affected by the
methods used to collect, store and analyse the crime samples, as
well as by the interpretation of a profile. Therefore, authorities
must recommend forensic laboratories be accredited for DNA testing
so as to standardize methods and quality.
is important to remember that the relevance of DNA profiling must
be assessed in the context of evidence in a case, since a match
between crime scene DNA profile and a suspect profile does not necessarily
prove guilt in the absence of other evidence. Human error or contamination
may contribute to a match between a profile from a crime scene sample
and a profile from an innocent person.
addition, a suspect's DNA may be introduced to a crime scene before,
during or after the crime for reasons unrelated to the suspect's
involvement in the crime. Also, DNA may be introduced to crime scene
by inadvertent or deliberate tampering.
Conversely, DNA profile exclusion does not necessarily
mean innocence. In a rape case, for example, a suspect may not contribute
to the semen sample, but may have been involved in the crime by
restraining the victim.
Once again, DNA profiles must always be interpreted in the context
of all available evidences.
and victimless cases are a serious problem for the Department of
Police in Sri Lanka. One of the solutions that we are suggesting
is the establishment of national forensic DNA databases like in
many European and certain Asian countries like China.
profile databases are rapidly proving to be valuable aids in criminal
investigation although there could be certain legal and ethical
questions in collecting and storing DNA profiles in databases. Everyone
arrested for any offence that carries a prison term must be obliged
to provide a DNA sample.
samples are the profiles generated from them and can be retained
by the police and entered in a National DNA Data Bank of Sri Lanka.
A DNA profile database can be established for all military and police
workers as a start and samples be collected at the time of their
recruitment. This will facilitate the issuing of death certificates
soon after a violent incident.
a matured justice system
DNA profiling and establishing databases for all citizens
would be the ideal and fairer policy than profiling only certain
individuals, but the cost factor, ethical and legal barriers might
strong leaders must assure the citizenry that these databases will
be used only for criminal investigations and the rights of all citizens
will be honoured. Over the next decade, it will be increasingly
important for all of us to understand the workings of these technologies
and we believe that Sri Lanka can be in the forefront of small nations
in leading the way.
order to protect society and individuals from potential abuses,
Sri Lankans should request their government to pay attention towards
using DNA based evidences.
and technicians must be given proper training prior to their recruitment.
Indirectly, this will open up a new avenue of employment in Sri
Lanka. Police, lawyers, judges and the public must be informed of
the potential and pitfalls of forensic DNA profiling so as to evaluate
it and question it intelligently.
addition, sufficient funding must be allocated by the government
to ensure that all suspects have full and impartial access to this
powerful new technology and that everyone is constitutionally protected.
S.K. Ballal is Senior Professor, Department of Biology, Tennessee
Technological University, Tennessee, USA and. Suneth Sooriyapathirana
is a Lecturerin the Department of Molecular Biology and Biotechnology,
University of Peradeniya)