Download ElizabethGarzaWritingFolder

Garza 1
Elizabeth Garza
Thomas
English
21 February 2012
Forensics
Forensic science is used for the purpose of the law. It provides scientific evidence
in courts of law, and in criminal investigations and trail. Examples of forensic science
include the use of gas chromatography to identify drugs, Deoxyribonucleic Acid (DNA)
profiling to help identify a murder suspect from a bloodstain found at the crime scene.
From examining hair follicles in a lab to scouring a crime scene looking for left behind
clues, forensics is a big part of the crime world. It happens every day. It can be little
complicated but great minds have found true suspects. A real crime scene is long, takes
patience, and involves important documents. CSI is a media franchise of American
television programs in which deals with forensic scientists as they unveil the
circumstances behind mysterious and unusual deaths and crimes committed.
At a crime scene an investigator finds a piece of clothing with a blood
spot. Now the investigator analyzes the DNA from the blood spot. If the blood is touched
by the hand without a glove the blood can get contaminated with another’s DNA and all
the data is ruined. Therefore investigators wear gloves at a crime scene when touching
clues. New technologies are being produced to determine ones DNA. DNA must be
amplified by a Polymerase Chain Reaction (PCR). The PCR method involves denaturing,
annealing, and extension, which are performed in an instrument called a thermalcycler.
This machine take the DNA and is placed in a reaction tube containing buffers, primers,
nucleotides, and an enzyme known as Taq Polymerase. During the denaturing step, the
Garza 2
mixture is subjected to high temperatures so that the double strands of DNA separates.
Next, the temperature is lowered to one that allows for annealing of the specific primers
to their sequence counterparts of the DNA of the sample. Finally, the temperature in the
thermalcycler changes to the optimal temperature for the enzyme Taq Polymerase, which
extends the regions between by the primers by adding the nucleotides, thus making a
copy. The same reaction repeats over many cycles of these three steps resulting in an
exponential amplification of the regions between the primers. DNA sequences are put
into a computer which is used to calculate and store the data. The samples and
information identifies the gene sequence and looks for a math with a suspect. Though
revolution forensics is being high-tech. DNA is reaching a high point where investigators
have best chances of finding a math to identify their main suspect. The new technologies
that are out are helping investigators move a lot faster in finding their suspect. Before
high-tech machines started coming out, it took some time to determine the right person.
The work of forensic laboratories is varied and complex. Technical analyses performed
must be able to forestall or defeat any challenge. To provide the best service possible to
the criminal justice system, forensic laboratories must stay abreast of and access to the
latest technology and methods.
Blood Stain Pattern Analysis is one of the highly special areas of forensic science
that is important to crime scene processing. Crime scene technicians are called to often
horrifying scenes to gather crucial evidence regarding violent crimes. Bloodstain pattern
analysts use their ability to determine the type of weapon used, the direction of travel of a
victim or suspect, the trajectory of a projectile, the number of wounds a victim may have
suffered, and how events unfolded during a violent crime. Blood spatter experts work
Garza 3
alongside criminal investigators and work closely with other analysts. Due to the nature
of the job, they spend a lot of time around hazardous body fluids, so exposure is always a
danger if proper precautions are not taken. The work shift is typically standard, Monday
through Friday during traditional business hours. However, blood splatter analysts may
be subject to call out and can find themselves working at all hours, any time a crime
scene is discovered. Most bloodstain analysts work for large metropolitan police
departments or state-run crime laboratories. Blood spatter, or bloodstain pattern
interpretation, is a technique that seeks to piece together the events that caused bleeding.
Knowing how the blood got on the wall or other surface can be helpful in determining if
a crime was committed and if the blood is evidence in that crime. The blood spatter
pattern can tell a trained investigator much about what crime may have been committed
and rule out other types of crime. Together with other evidence, blood spatter can be very
useful in piecing together what took place, identifying the victim, and determining who
was responsible. One of the first things that a forensic investigator needs to do when
examining a blood spatter is to verify that the material is indeed blood. This can be
determined by using tests that are portable enough to be used right at the scene. Later,
tests will be done to determine if the blood is animal or human in origin and even to
narrow down the people from whom the blood may have come. In the actual spatter
analysis, a forensic investigator determines the trajectory of the blood. By measuring the
shape of the bloodstain on a surface, the direction of movement can be determined. As
well, the speed at which the blood contacted the surface can be approximated. This can
help distinguish, for example, between the rapid movement of blood that can be produced
Garza 4
by a gunshot and the severing of an artery in opposition to the slower movement of blood
from a minor cut.
If blood originated some distance away from a surface, the force of impact will
cause the blood to break up into smaller drops. Thus, a blood spatter consisting of larger
drops with a trail of smaller drops can tell an investigator much about how the blood got
there and where the blood came from. The trained eyes of an experienced investigator
remain one of the most powerful tools in blood spatter analysis. Specialized analytical
computer programs are also available. Such detailed analysis can be important if the
blood spatter is presented as evidence in a legal case.
DNA is the most important part of identifying a suspect at a crime scene. Finding
clues, small or big clues can lead to your person. It can be very difficult identifying a
suspect. An investigator can have a hard job at times or an easy one. There are special
things to look for at a crime scene. For example, finding blood, shoe prints, and hair. An
investigator has to look hard for theses things. If he or she has found these clues they
have to examine them and come out with some DNA. Finding matches with your clues
can be a great lead away, you also have been confident in yourself and your clues. DNA
identification can be quite effective if used correctly. Portions of the DNA sequence that
vary the most among humans must be used. Also, portions must be large enough to
overcome the fact that human mating is not absolutely random. Consider the scenario of a
regular crime scene investigation, for example: Assume that type O blood is found at the
crime scene. Type O occurs in about 40-45% of Americans. If investigators type only for
ABO, then finding that the accurate “suspect” in a crime is type O really doesn’t reveal
Garza 5
very much. If, in addition to being type O, the suspect is a blonde, and blonde hair is
found at the crime scene, then you now have two bits of evidence to suggest who really
did it. However, there are a lot of Type O blondes out there along with brunettes.
If you find that the crime scene has footprints from a pair of Nike Air Jordan’s or another
distinct type of shoe and the suspect, in addition to being type O and blonde or brunette,
he is also wearing Air Jordan’s or another specific shoes with the same tread design, then
you are much closer to linking the suspect with the crime scene, assuming it is a male. In
this way, by accumulating bits of linking evidence in a chain, where each bit by itself is
not very strong but the set of all of them together is very strong, you can argue that your
suspect really is the right person, as long as you have all the important evidence. With
DNA, the same kind of thinking is used. You can look for matches at a number of
different locations on the person’s genome; one or two, maybe three aren’t enough to be
confident that the suspect is the right one, but four or five can be used and are used and a
match at all five is rare enough that you, a prosecutor or a jury can be very confident, that
the right person is accused an acquitted.
Garza 6
Works Cited:
"Advice about a Career in Forensic Science." Advice about a Career in Forensic Science.
Web. 21 May 2012.
"Behavioral Effects of Drugs, Toxins & Alcohol." Behavioral Effects of Drugs &
Alcohol. Web. 21 May 2012.
"DNA Forensics." DNA Forensics. Web. 21 May 2012.