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Criminal Mischief: The Art and Science of Crime Fiction: Episode #17: DNA and Twins

DNA Replication

 

LISTEN: https://soundcloud.com/authorsontheair/criminal-mischief-episode-17-dna-and-identical-twins

PAST SHOWS: http://www.dplylemd.com/criminal-mischief.html

SHOW NOTES:

For years it was felt that the DNA of identical twins was indeed identical. Since they come from a single fertilized egg, this would seem intuitive. But, nature likes to throw curve balls—and the occasional slider. After that first division of the fertilized, and after the two daughter cells go their way toward producing identical humans, things change. And therein lies the genetic differences between two “identical” twins.

LINKS:

One Twin Committed the Crime—but Which One?: https://www.nytimes.com/2019/03/01/science/twins-dna-crime-paternity.html

The Claim: Identical Twins Have Identical DNA: https://www.nytimes.com/2008/03/11/health/11real.html

The Genetic Relationship Between Identical Twins: https://www.verywellfamily.com/identical-twins-and-dna-2447117

Identical Twins’ Genes Are Not Identical: https://www.scientificamerican.com/article/identical-twins-genes-are-not-identical/

Rare Australian Twins Are “Semi-Identical,: Sharing 89 Percent of Their DNA: https://www.inverse.com/article/53633-semi-identical-twins-share-78-percent-of-dna

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Criminal Mischief: Episode #07: Famous and Odd DNA Cases

 

Criminal Mischief: Episode #07: Famous and Odd DNA Cases

LISTEN: https://soundcloud.com/authorsontheair/criminal-mischief-episode-07-famous-odd-dna-cases

PAST SHOWS: http://www.dplylemd.com/criminal-mischief.html

 

FAMOUS AND ODD DNA CASES NOTES:

 

Colin Pitchfork: The Beginning

http://aboutforensics.co.uk/colin-pitchfork/

Timothy Wilson Spencer, The Southside Strangler” First US DNA Conviction

(David Vasquez—first to be exonerated by DNA)

https://en.wikipedia.org/wiki/Timothy_Wilson_Spencer

http://www.digitaljournal.com/article/352011

Brown’s Chicken Murders:

https://en.wikipedia.org/wiki/Brown%27s_Chicken_massacre

https://chicago.cbslocal.com/2018/01/08/browns-chicken-massacre-25-years-anniversary/

Lonnie Franklin, The Grim Sleeper: Familial DNA

https://en.wikipedia.org/wiki/Grim_Sleeper

https://www.rollingstone.com/culture/culture-features/grim-sleeper-serial-killer-everything-you-need-to-know-252246/

James Lynn Brown: Familial DNA

https://www.ocregister.com/2012/12/04/family-members-dna-solves-1978-killing/

Gary Ridgway, The Green River Killer

https://en.wikipedia.org/wiki/Gary_Ridgway

Pierre G: Kiss DNA Foils Jewel Thief

https://www.telegraph.co.uk/news/worldnews/europe/france/10616806/French-jewellery-thiefs-fate-sealed-with-a-kiss-after-conviction-from-DNA-on-victim.html

David Stoddard: Dog Bite DNA Case

https://www.news5cleveland.com/news/local-news/akron-canton-news/dna-from-dogs-mouth-solves-barberton-home-invasion-suspect-david-stoddard-also-charged-with-murder

Maggot DNA Case:

https://www.ncbi.nlm.nih.gov/pubmed/22971153

Willow Martin Arson Case and Potato DNA:

http://www.courant.com/breaking-news/hc-strippers-arson-drugs-0713-20160712-story.html

https://www.mycitizensnews.com/news/2018/05/woman-sentenced-to-8-years-for-arson/

 

 
 

Criminal Mischief: Episode #06: Is It Harder To Write Crime Fiction Today?

AOTA Graphic

 

Criminal Mischief: Episode #06: Is It Harder To Write Crime Fiction Today?

LISTEN: https://soundcloud.com/authorsontheair/criminal-mischief-episode-06-is-it-harder-to-write-crime-fiction-today

Is It Harder To Write Crime Fiction Today? Notes:

Do modern forensic science and police investigative techniques make creating compelling crime fiction more difficult? Are there simply too many balls to keep in the air? Too much to consider? Or is now little different from then?

The Past, the present, and the future

Forensic Science timeline—-a fairly new discipline

Basic Science, then Medicine, finally forensic science

Personal ID

Visual
Bertillon
West Case
Facial recognition
Behavioral Profiling

Prints, ABO type, DNA, DNA Phenotype

Fingerprints—-then and now

Vucetich—the Rojas case
Stella Nickell Case
Touch DNA
Touch Toxicology

Toxicology

From arsenic to GC/MS

Blood Typing

ABO can exclude but not ID

DNA

Nuclear
Mitochondrial
Familial—Grim Sleeper case
Phenotypic Analysis

Electronics

Cell phones, computers, emails, texts, VMs

LINKS: 

Forensic Science Timeline: http://www.dplylemd.com/articles/forensic-science-timeline.html

History of Fingerprints: http://onin.com/fp/fphistory.html

Brief History of Poisons and Forensic Toxicology: https://www.okorieokorocha.com/poisons-and-forensic-toxicology/

History of Forensic Ballistics: https://ifflab.org/the-history-of-forensic-ballistics-ballistic-fingerprinting/

FORENSICS FOR DUMMIES: http://www.dplylemd.com/book-details/forensics-for-dummies.html

HOWDUNNIT:FORENSICS: http://www.dplylemd.com/book-details/howdunnit-forensics.html

Stella Nickell Wikipedia: https://en.wikipedia.org/wiki/Stella_Nickell

DNA Profiling: https://en.wikipedia.org/wiki/DNA_profiling

Mitochondrial DNA: http://www.dplylemd.com/articles/mitochondrial-dna.html

Familial DNA: http://www.dnaforensics.com/familialsearches.aspx

Grim Sleeper/Lonnie Franklin case: https://en.wikipedia.org/wiki/Grim_Sleeper

Is DNA Phenotyping Accurate: https://www.smithsonianmag.com/innovation/how-accurately-can-scientists-reconstruct-persons-face-from-dna-180968951/

DNA Phenotyping Examples: https://snapshot.parabon-nanolabs.com/examples

Bertillon and the West Brothers: http://www.nleomf.org/museum/news/newsletters/online-insider/november-2011/bertillon-system-criminal-identification.html

 

Does Your DNA Contain Your Image?

DNA-Based Sketches

 

To say that DNA had revolutionized criminal investigations would be a huge understatement. Prior to DNA profiling, identifying a suspect with absolute certainty was more difficult. Fingerprints would work, of course, and eyewitness accounts, though flawed in many ways, could also help. But a criminal leaving behind biological evidence such as blood, semen, saliva, hair, skin cells, and other little bits, offers a method of identity that is second to none. DNA profiling has been used to catch many a criminal. But, in order for it to do its work, there must be something for the DNA analyst to compare the crime scene sample against. The DNA database, CODIS, helps because it stores millions of DNA profiles and if the perpetrator is in the system, a match can be made. But if he is not, the database is of little help.

DNA analysis can reveal the gender of the person who left behind the sample quite easily. But our DNA controls more than that. It determines how tall we will be, what our hair and eye color will be, our intellectual level, our ability to play music, and many other things. Familial DNA has been used to narrow down unknown samples to a smaller group, such as an extended family. And lately, this is been used in conjunction with the various ancestral databases to solve some crimes. But a newer technique offers another tool on the DNA front. It’s called DNA Phenotyping.

The principle seems simple: Since our DNA determines what we look like, would it not be possible to take a DNA sample and then create an image of the individual it belonged to? Maybe. At least great strides have been made in that regard. A case in point is that of research biologist Le Bich-Thuy, who was raped, battered, and strangled 24 years ago. DNA obtained from that scene was subjected to DNA Phenotyping and an image of the individual who likely perpetrated the crime was generated. Not only that, the image was age altered so that it would more accurately reflect what he might look like now. Fascinating case.

 

Did “Tourista” Kill the Aztecs?

Many people who travel to other countries end up suffering from Tourista, or Traveler’s Diarrhea, a gastrointestinal upset that is manifested by diarrhea and sometimes nausea and vomiting. It’s due in many cases to E. coli, which is found everywhere. Various regions will have different strains of E. coli. Residents of the area are able to live quite compatibly with it. The problem arises when you travel to a new area and are exposed to a different strain. Until the body readjusts to this foreign strain, gastrointestinal symptoms can occur. Usually, this is mild and inconvenient and after a few days everything settles down and life goes on.

Tenochtitlan1

 

Not so with the Aztecs. In 1545, an epidemic swept through the Aztec nation killing millions, perhaps as much as 80% of the population. Twenty years earlier an epidemic of smallpox had come through and damaged the population and 20 years later another epidemic swept through killing another huge portion of the population. There have been many infectious processes indicted for the 1545 plague, which the Aztecs called cocoliztli. Smallpox, measles, mumps, and various other infectious entities have been blamed for this. But what if it was actually a gastrointestinal bacterium that did the damage?

The symptoms the victims suffered seem to have been gastrointestinal. Apparently, there was bleeding, vomiting, diarrhea, and splotches on the skin. These symptoms and signs suggest a form of enteritis and that’s exactly what the bacterium salmonella does.

New evidence suggests that it might be a strain of salmonella that caused this problem, in particular, salmonella Paratyphi C. Genetic research using DNA obtained from the teeth of those who succumbed to the epidemic indicate that this might be the case. Where it came from is another question. Did it come with the influx of Europeans? Or perhaps extend south from northern Mexico? This is still being debated and researched but it does appear that salmonella may have been the culprit in the epidemic that destroyed the Aztec Empire.

Salmonella has been responsible for other public health crises, one of the most famous being Mary Mallon, aka  Typhoid Mary. In this situation, the type of salmonella was salmonella typhi, which causes typhoid fever.

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Can Your DNA Reveal Your face?

Parabon_Snapshot_Workflow_Diagram

You’ve seen it on TV. The CSI-types plug in a DNA sample and like magic a 3-D, holographic image of the bad guy pops up like a ghost. Or some such stuff. Pretty far-fetched. Or is it?

DNA analysis is primarily used for comparison, meaning that a sample obtained from a crime scene is compared with a sample obtained from a suspect to see if the DNA from the scene belongs to the suspect, or not. This is how many cases are solved. DNA is highly accurate for making such comparisons.

But what if there is no suspect and therefore no DNA to compare with that obtained at the crime scene? The police will then go to databases such as CODIS to see if the perpetrator has DNA on file from previous crimes. Often this helps. Often a match is made this way. But what if the perpetrator is not in the system? The police are back to square one.

DNA can of course reveal the sex of the individual very easily. It can also often determine hair and eye color and other physical features. But can it give a “picture” of the individual who left the DNA behind? Not yet, but things are moving that way.

Here are a few fun articles on this technique:

DNA Phenotyping Recreates the Face of an Alleged Serial Killer: https://www.forensicmag.com/article/2016/08/dna-phenotyping-recreates-face-alleged-serial-killer

First DNA-Phenotyped Image of “Person of Interest” in Double Homicide: https://www.forensicmag.com/article/2015/01/first-dna-phenotyped-image-person-interest-double-homicide

Phenotyping and Cold Cases:
https://www.defrostingcoldcases.com/phenotyping-cold-cases/

 

Bugging Your DNA

Mosquito

 

Everybody hates mosquitoes. They irritate, they bite, and they carry disease. In fact they are likely the most deadly creature on Earth since they spread malaria through many regions of the world. They also spread things like yellow fever and Zika – – – and a host of other nasty little problems.

But can mosquitoes place you at a crime scene? If so, how would this work?

Let’s say investigators come to a murder scene and find a smashed and dead mosquito on the bed sheets near the corpse. It might be reasonably assumed that this mosquito bit someone and that person then killed it, leaving it where it fell. Could that be used to ID the killer?

It appears that human blood can remain in the mosquito’s stomach for up to two days. And if this is extracted, it can be used in DNA profiling. So the mosquito at the crime scene could be collected and tested, and if DNA were found, a profile could be generated and lead back to the killer.

Esoteric, but fascinating.

 
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Posted by on August 31, 2017 in Crime Scene, DNA, High Tech Forensics

 
 
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