This week’s blog post in not light hearted or funny like my
other posts in the past. However, this week I want to share something that is
both interesting and serious.
Back in the early 50’s, if someone went missing, or came up
murdered, the technology used to capture the criminal was not nearly as amazing
as what we have today. Specifically, there was a case in 1948 where a woman was
brutally raped and murdered in a small English community. There were no witnesses,
no one knew anything about that tragic night. However, the cops were able to
find one thing left behind that would help them solve this murder case. The
murder left a fingerprint behind on a glass bottle found at the crime scene. After
gathering over 45,000 fingerprints, the murderer was finally found and
convicted.
Fingerprints are very unique, and no two people in the world
have the EXACT same prints. This is why fingerprints are one of the first
things looked for in a criminal investigation.
But what happens if the investigators do not find any fingerprints left
behind? How are they supposed to catch the criminal then?
The answer is DNA. DNA can be found in hair follicles, spit,
blood and even sperm. DNA is just like a fingerprint as in it is what makes each
person unique. It was in the 1980’s when
research in molecular biology reached new heights.
When hair, blood, or sperm, are left behind, molecular
biologists can take samples back to the lab and get to work. Through techniques
like DNA isolation and hybridization, scientists are able to create a different
type of “fingerprint” that matches the criminal. This DNA fingerprint can be
used and compared to potential suspects. After taking evidence from the crime
scene, DNA analysis can begin. This process can be broken down into 4 steps:
DNA extraction; DNA quantification; DNA amplification; and Detection of the DNA
amplified products. In the 90’s it was finally legal to take these DNA analyses
to the court and put criminals behind bars.
There are four main methods used in forensics for human
identification that I want to talk about. Autosomal STR profiling is first on
the list. STR stands for short tandem repeats. STRs were discovered in the
1980s. Since the 80’s, STRs are known as the “gold standard” for human
identification. STR profiles that are obtained from the samples gathered at the
scene are compared to profiles from known suspects. STR can also be used in
paternity or maternity cases as well. The main advantage of STR markers is the
fact that they can test in a rapid way which allows for increased degree in the
identification of different biological samples. The next method is Analysis of
the Y‐chromosome. Since the Y chromosome can only be found in males, Y‐STR
profiling is very useful in identifying the gender of the suspect. Analysis of
mitochondrial DNA (mtDNA) is another common method used for human
identification. The cool thing about this analysis is, it has the ability to
analyze biological samples that are old or severely degraded, and it can
analyze biological samples that contain a low amount of DNA. This method is
great for bodies or crime scenes that have been found days or even weeks after
the fact. The final method I am going to
talk about is Autosomal single‐nucleotide polymorphisms (SNP) typing. This
method is good for testing samples that have little DNA. This method was used
in identifying the victims from the World Trade Center disaster in 2001.
We can thank a molecular biologist for determining custody
of a child through paternity or maternity tests, identifying victims from
disasters or crimes, and granting freedom to innocent people convicted to
prison.
Sources:
https://www.intechopen.com/books/forensic-analysis-from-death-to-justice/molecular-genetics-and-its-applications-in-forensic-sciences
It's interesting to see all the implications or methods that DNA fingerprinting has in human identification. I actually thought there were only two methods, but since the 1980's molecular biologist have come very far! I think the most interesting thing was that the SNP typing method was used to identify victims in the 2001 disaster. Great blog!
ReplyDeleteLoved your blog! It was interesting and informative. I did not know much about short tandem repeats prior to reading your blog. I think its pretty cool how they can be used for human identifications.
ReplyDeleteI always love reading about anything forensics. I never had heard about SNP, so it was nice learning something new. Great post!
ReplyDeleteI appreciate your enthusiastic and enlightening posts pertaining to forensic science! I had no idea about the various methods used in DNA fingerprinting. I guess I just assumed there was one method as used on crime shows like CSI. I would love to read a blog post in the future all about the SNP method being used after 9/11 to identify the victims. It is neat how in dark times and times of tragedy, modern science and technology can be used to help make the situation better.
ReplyDeleteI think its so cool how science is able to determine who a person is and put these awful people behind bars. That is one thing a criminal can never avoid leaving behind, their DNA. I love how you tied forensics into molecular biology. Very clever.
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