Transcript Forensic Science

Forensic Science
By: Garrett Dekan
A forensic scientist is a someone who uses
their scientific training to help convict
people who have committed crimes.
They’ll assess the evidence at the crime
scene and then present it in court.
Types of Forensic Scientists:
•Forensic Anthropologists—analyzes human remains
•Forensic Odontologists—examine teeth carefully
•Forensic Pathologists—determines cause of death
•Forensic Toxicologists—help with cases of poisoning
and drug use
•Forensic Entomologists—Studies insect evidence
•There are also computer/digital specialists and
pychologists
Determining Age:
A forensic scientist first must collect the evidence without
contaminating it. After collecting it they must analyze it. For
example, forensic anthropologists will examine the remains of
the body. They will check the growth rate of the bones.
Ossification (bones become larger, thicker, and fuse together
in teenage years) is a good guide to how old a child is. The
collarbone is the last thing to finish growing at 28 years old,
so it can also help to determine age. Anthropologists look for
spikes on the vertebrae, the wearing of teeth, and joints with
arthritis in elderly victims.
Determining Gender:
Forensic scientists also try to determine gender. When they
are determining gender they look at the skull and hip
bones. When looking at the skull, they look at the ridges
above the eyes, the bone just below the ear, and the
occiput (bone at the lower back of the skull). They also look
for the width of the hips because men’s hips are narrower
than women’s because women’s were made for bearing
babies.
Determining Height:
Forensic anthropologists attempt to recreate the
skeleton from the remains of the bones to determine
the height. After recreating the skeleton, they must
add four inches to the height for the missing tissue
and muscle. They use longer bones to help estimate
the height. For example, the height of a person is
usually two and two thirds the length of the femur.
However, height does also depend on the race and
gender so it isn’t completely reliable.
Defects and Injuries:
Some infectious diseases, poor diet, cancer,
and birth defects, like spina bifida, can be
seen in bones. Broken and mended bones
are easily detected. Arthritis can occur from
hard labor. Violent deaths can leave clues.
Some examples are, a bullet wound leaves a
round hole, a sharp weapon leaves chips in
the bone, and fractures would indicate
violence as well. Some fractures, however,
can occur after the death, so the
anthropologists have to be careful.
Fingerprints:
There are three types of fingerprints. The first is visible fingerprints, which
are visible. Visible fingerprints are prints left in grease, blood, ink, or other
colored substances. Plastic fingerprints are also visible. They are prints left in
soft substances like clay, wax, or soap. The last type of fingerprint is a latent
fingerprint. Latent fingerprints are invisible fingerprints that are left by our
body’s oils and greases. Fingerprint patterns are classified in three basic
types: arches, whorls, and loops. Loops are lines that start on one side of
the finger, loop around and then leave on the same side of the fingerprint as
it started. Arches are prints that start at one side of the finger, make hills,
then end at the other side of the finger. Whorl fingerprints are prints that
make circles and don’t start or end on a certain side of the finger.
Fingerprints, as you know, are different in every person. Fingerprints aren’t
different because of the shape or pattern, but because of the ridge structure.
About 200 million fingerprints are in the FBI Identification Division. Modern
computer technology can be used to find a potential suspect in minutes.
Loop
Whorl
Arch
DNA:
DNA is made of guanine, cytosine, thymine, and adenine. You could
describe DNA as a ladder that is curled around continuously with
some 3 billion rungs attached to it. These rungs are arranged
differently for everyone. A small part of the DNA strand is used for
a person’s appearance, the rest of it is “junk”, but this “junk”
sometimes helps a forensic scientist determine a person’s identity.
The “junk” consists of small sequences of the base chemical called
short tandem repeats or STRs. These STRs continually repeat from
end to end. The number of times the STR repeats changes
noticeably from person to person. Usually the STR only needs to be
counted to thirteen before a match is made. Forensic scientists
separate a DNA strand from the nucleus by using a mixture of
chloroform and phenol. This typically isn’t enough DNA to analyze,
so it is artificially increased by polymerase chain reaction or PCR.
This method multiplies the DNA so it is big enough to be analyzed
and used as evidence.
Court:
DNA evidence can be very convincing if there is
enough non-DNA evidence to support it. If, however,
there is little to no additional evidence, then DNA
evidence is basically useless, because of mistakes
such as contamination. Analyzing DNA will hopefully
progress more in the distant future. They’re hoping
one day a single drop of blood will be able to
determine the height, race, and maybe even the
facial structure of that suspect. This will allow DNA
evidence to be used as more reliable evidence in
court.