DNA Profiling

This article discusses DNA profiling, its importance in forensic investigations, and the techniques used. It explores the composition of DNA, the variations in coding and non-coding DNA, and the role of DNA profiling in identification. The article also covers the collection of blood samples and fingerprints from a crime scene. Find study material and solved assignments on DNA profiling at Desklib.

Running Head: DNA Profiling
DNA PROFILING

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Table of Contents
Introduction.................................................................................................................................................2
Discussion...................................................................................................................................................2
Conclusion...................................................................................................................................................4
References...................................................................................................................................................6

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Introduction
From crime to the criminal is a very difficult journey. A clever criminal commits the crime and
leaves the spot. Investigation agencies reach for investigation. The investigating officer will lift
all physical as well as biological evidence from the crime scene; and seal it for analysis and
comparison. A police officer is a lawyer and a doctor in miniature, and very often, he in his
keenness on points of law and on points of medical jurisprudence forgets his job. His job is
essentially different from that of a lawyer and doctor. In these areas, he may get assistance from
other sources, but as far as his job is concerned, he gets very less assistance. The work of
investigation starts from the spot of occurrence, hence the relevance of the crime scene. Do all
depend upon whether he takes a correct step on the site of occurrence or not? The only dictionary
which, an investigating officer can consult to get any aid in solving the riddle is the site of the
crime. All human actions whether crime or not are governed by the time and place factors (Gill,
2001).
In the given scenario the two primary pieces of evidence that have been collected from the crime
scene are:
1. Blood samples
2. Fingerprints
The evidence collection team would collect dried blood from the blood stains from the sink,
mattress and the floor and another team would collect fingerprints from the wash basin and the
container of the cleaner which was used to wash away the stains. Moreover, the cabinet on top of
which the drug samples were found will also be examined for fingerprints, and if any is found,
then they will also be collected.
The reason for choosing these two forms of evidence and their testing has been discussed in the
rest of the essay.

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Discussion
The journey for the scientists to conclude that DNA (an acronym for deoxyribonucleic acid)
found in every nucleated cell of the body can play a vital and conclusive role in the identification
of the individuals had not been facile. In the initial stages of advancement, Scientists hardly
knew the composition of the nucleus. Rather, it was not known that an organelle named nucleus
existed. The only thing known was Cell. Incidentally, nucleus, the house of DNA, was the first
organelle to be discovered by Antoine Phillips Van Leeuwenhoek (1632-1723) while he was
observing the red blood cells of a fish, the Salmon. He observed oval bodies that he named as
lumen, the nucleus. However, he could not state anything about the contents of the oval bodies
he had observed. It is also worth to be noted that the mammalian mature RBC‘s do not possess
the nuclei. Franz Bauer also described nucleus in 180438, but the more detailed version was
given by Robert Brown in 183139 who coined the term ―cell nucleus‖. His work suggested that
nucleus played a key role in fertilization and development of the embryo in plants, this was the
centre of cellular creation. However, the composition of the nucleus was still not known. It was
Friedrich Miescher (1844-1895) who in the year 1869 discovered a substance in the cell nucleus
and named it as "nuclein". DNA profiling for forensic purposes originated in the early 1980s
following the rape and murder of Lynda Mann and Dawn Ashworth in Leicester, England,
occurring in identical circumstances. Post these murders; Police turned to Professor Alec
Jeffrey‘s, who was carrying out research into diseases caused by mutations in DNA (Archak,
2000). Hence, the present work makes a modest attempt first to analyze what is there in DNA
which when processed through DNA profiling makes it infallible and a unique identifier for
identification, Secondly, being an identification tool whether it aids or obstructs in investigation,
Thirdly, whether it should be considered as an ultimate diviner of guilt or innocence, Fourthly, in
an attempt to enhance the modes of criminal investigation, whether incidentally DNA profiling
or the process adopted as such in DNA profiling impinge upon the civil liberties or not and
finally, whether DNA Profiling can play a fundamental role in investigations and trials. DNA in
all humans is the same (coding DNA). However, there are certain places with differences, and
these variations don't match between two humans except in monozygotic twins (non-coding
DNA) (Kimpton et al., 1993). Coding DNA has a role to play in the makeup of a gene/protein,
but non-coding DNA has no such role. DNA is made of nitrogenous bases, sugar, and phosphate
bonds (Mowat & Strobeck, 2000). The sugar and phosphate that make up the outer structure are

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same in everybody. However, the difference lies only in the sequence of bases. It is the
combination of these bases that make DNA of an individual unique. Interestingly, the junk DNA
shows variations amongst individuals and is, therefore, utilized for identification purposes
through DNA profiling (Amos et al., 1993).
Different techniques have been developed by scientists to develop a profile from the DNA of a
person inter-alia includes RFLP (restriction fragment length polymorphism), probably the first
and the foremost technique developed by the scientists. Genetic researchers had located certain
areas on the DNA, which varied from an individual to an individual; and RFLP examined those
differences (Kimpton et al., 1994). In mid-1980s polymerase chain reaction (PCR) Technique
was developed by a forensic scientist, which was a great leap in the direction. In this process,
DNA or its fragments could be replicated any number of times. So, it had an advantage over
RFLP as it took less time to process and give the result.
Further, it also helped to test small-degraded samples of blood or other biological fluids, which
were then multiplied millions of times thereby making it possible to analyze smaller units of
DNA and could give results which were more accurate. In the 1990s a process named short
tandem repeats (STR‘S) was adopted by FBI (Federal Bureau of investigation) where smaller
segments of DNA were looked for those varied among individuals, and thus was used as the
national standard for forensic identification. Mitochondrial DNA (mtDNA) is still under
development, which examines DNA inherited from the maternal side (McGinnity et al., 1997).
Sample collection
Collecting samples from a crime scene is a difficult job. In the given situation the crime scene in
the 123 Fake street seemed to be contaminated by the officers in their early investigation. To
collect the samples two teams were deployed, one of which will collect blood samples and the
other one will collect fingerprint collections.
Blood sample Collection: In the crime scene of 123 Fake street there are primarily 3 places
where blood samples were notices, and they were on the floor, on the cleaning cloths in the sink
and on the carpet. Collecting the samples from the floor can be done by scraping off the dried
blood off the floor using scalpels and storing them in marked containers. Next the sample is to be
collected from the cleaning cloth by following by a similar process, but it should be made sure

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that the scraping is done with the minimum force so that the fibres don't get scraped off with the
dried blood. Lastly the sample is to be collected from the carpet which can be a tricky job as the
carpet is really woolly and with every scraping bits of fiber is going to come out with the sample
so it advisable that the sample should be collected with the fibre and later on in the lab the fibres
will be eliminated from the sample.
Fingerprint Collection: This team faces the biggest challenge as there is a possibility that the
crime scene has been contaminated and could contain unnecessary prints left behind by
inattentive police officers or initial investigation officer. Firstly the team must check the entire
scene with UV light and identify certain areas with high concentration of fingerprints and then
collect them following standard fingerprint collection methods.
Conclusion
Scientific advancements have made the barbaric and archaic methods of enforcing a social order
in the society, especially the investigation, redundant. Where for a democratic setup, peace and
harmony are the inevitable components; commission of crimes can also not be avoided.
However, new scientific methods can help in the prevention and early detection of the offenders.
Once, crime is committed, the race begins to decipher the most vital questions; who, why, where
and how. The most important of all is the identification. Identification, either of the victim or the
accused, is the core and the key question for each forensic investigation. However, it may not be
so facile in cases of bodies of victims beyond recognition; cases, where accused, have made
attempts to conceal their identity; cases where the perpetrator is not known to the victim; and in
planned crimes (Gill et al., 1994). However, with the passage of time, the most infallible
traditional method of identification, i.e. Dactylography (fingerprinting) seemed to have failed as
the accused have developed modes of concealment. The consequences of non-identification are
deleterious for the security, solidarity, and social order of the society. Firstly, the threat of breach
of social order continues as there is the likelihood that such a person may again commit a similar
felony or more heinous one with an enhanced level of confidence. Secondly, it would also
encourage the others thinking on the symmetrical lines. Lastly, it would shake the faith reposed
by the victim or his family members in the criminal justice system compelling him or his family
members to take vengeance in their style and way (Mills et al., 2003).

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References
Amos, B., Schlotterer, C., & Tautz, D. (1993). The social structure of pilot whales revealed by
analytical DNA profiling. Science, 260(5108), 670-672.
Gill, P. (2001). Application of low copy number DNA profiling. Croatian medical
journal, 42(3), 229-232.
Gill, P., Kimpton, C., D'Aloja, E., Andersen, J. F., Bar, W., Brinkmann, B. & Nellemann, L.
(1994). Report of the European DNA profiling group (EDNAP)—towards
standardization of short tandem repeat (STR) loci. Forensic science international, 65(1),
51-59.
Kimpton, C. P., Gill, P., Walton, A., Urquhart, A., Millican, E. S., & Adams, M. (1993).
Automated DNA profiling employing multiplex amplification of short tandem repeat
loci. Genome Research, 3(1), 13-22.
Kimpton, C., Fisher, D., Watson, S., Adams, M., Urquhart, A., Lygo, J., & Gill, P. (1994).
Evaluation of an automated DNA profiling system employing multiplex amplification of
four tetrameric STR loci. International journal of legal medicine, 106(6), 302-311.
McGinnity, P., Stone, C., Taggart, J. B., Cooke, D., Cotter, D., Hynes, R, & Ferguson, A. (1997).
Genetic impact of escaped farmed Atlantic salmon (Salmo salar L.) on native
populations: use of DNA profiling to assess freshwater performance of wild, farmed, and
hybrid progeny in a natural river environment. ICES Journal of Marine Science, 54(6),
998-1008.
Mills, D. K., Fitzgerald, K., Litchfield, C. D., & Gillevet, P. M. (2003). A comparison of DNA
profiling techniques for monitoring the nutrient impact on microbial community
composition during bioremediation of petroleum-contaminated soils. Journal of
microbiological methods, 54(1), 57-74.
Archak, S. (2000). Plant DNA fingerprinting: an overview. AgbiotecNet International journal,
1-10.

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Mowat, G., & Strobeck, C. (2000). Estimating population size of grizzly bears using hair
capture, DNA profiling, and mark-recapture analysis. The Journal of wildlife
management, 183-193.
Tully, G., Bär, W., Brinkmann, B., Carracedo, A., Gill, P., Morling, N., ... & Schneider, P.
(2001). Considerations by the European DNA profiling (EDNAP) group on the working
practices, nomenclature, and interpretation of mitochondrial DNA profiles. Forensic
Science International, 124(1), 83-91.