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Even Identical Twins Have Different DNA

For years the dogma was that identical twins possessed DNA profiles that were not distinguishable from one another. But things are changing.

Fraternal (dizygotic) twins come from two eggs and two sperm and are as different as if born years apart. They are twins solely because they shared the mother’s womb at the same time. But, identical twins (monozygotic) come from a single egg and sperm. They are formed when the fertilized egg undergoes its first division and the two new daughter cells move apart, each then proceeding to form a separate individual. Since they came from the same fertilized egg, the share the same DNA. In fact, the two would be indistinguishable by standard PCR-STR DNA Profiling.

 

Twins

 

But, in reality, even identical twins have distinct DNA. We just weren’t able to see the differences. Before now.

As each twin embryo grows and develops in utero, and the cells continue to multiply, the replication (copying) of each twin’s DNA isn’t perfect. Minor errors or variations begin to appear so that by birth each Twin’s DNA is slightly different from its sibling. And as life goes on, each twin is subjected to different environmental stresses, which is turn alters each one’s DNA replication.

As opposed to STR, which looks at repeating short sequences of bases within the DNA strand, a newer DNA technique, known as Single Nucleotide Polymorphism (SNP), gives the examiner a complete DNA sequence of the strand being analyzed. That is the exact sequence of bases in each strand is determined and this can reveal the differences in the DNA of identical twins. Another newer technique known as High Resolution Melt Curve Analysis (HRMA) might offer still another method to make this distinction.

So even identical twins are not so identical.

Want to know more about DNA profiling? Check out the updated 2nd Edition of FORENSICS FOR DUMMIES.

 

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2 Comments

Posted by on May 2, 2016 in DNA, Uncategorized

 

Guest Blogger: Lisa Black: Everything Old Is New Again

EVERYTHING OLD IS NEW AGAIN

My character, Cleveland forensic specialist Maggie Gardner, is unrealistic in one respect—she still spends a lot of time at her microscope looking at tiny bits of trace evidence, hairs, fibers, paint, and glass.

No one does that any more. Well, maybe Abby on NCIS, but she’s the most unrealistic forensic person on screen, even though she’s so cute we don’t care.

Sure, on old episodes of Dragnet you can see some nerdy guy in a lab coat explain how these pollen spores are only found in one quadrant of the city, but that art had already died before I started in forensics in 1994. We got spoiled by DNA, by ‘absolutely yes’ or ‘absolutely no’ answers. No one wanted to hear that this red nylon was ‘consistent with’ the suspect’s shirt, because they wouldn’t be hearing how many red nylon shirts were manufactured, how many were sold in this area, and while we’re at it let’s hack into Macy’s sales figures and find out who they were sold to. Unlike television, forensic labs do not have databases of all this information and would probably be violating a few important laws if they did. Nope, ‘consistent with’ was all you got. Take it or leave it.

 

Polyurethane_Fibers

POLYURETHANE FIBERS

They left it. Microscopic analysis became more or less a thing of the past. Forensic techs today wouldn’t recognize a pollen spore or know what to do with it if they did. Fibers are ignored. Hairs are examined only to screen out candidates for, well, DNA.

Imagine my surprise, then, when I peruse the latest Journal of Forensic Sciences and stumble on an article about using something called palynological scanning to rapidly evaluate suspect and victim testimony.

 

pollen

POLLEN

Palynology, it turns out, is a fancy name for…pollen. Pollen and spores and other ‘microscopic entities’ of trees, shrubs and herbs. No hairs, fibers or paint, but you get the idea. This analysis proved useful in some cases of rape or assault, in situations where the victim and suspect both contacted the ground and pieces of the ambient flora could attach to their clothing.

 

trees

 

In one case the suspect said he and his victim engaged on a lawn behind a public building. The victim said he attacked in a heavily wooded area, the spot surrounded by beech, birch and sycamore trees. Each site had a distinct mix of items—palynomorphs– with complicated Latin names. The suspect didn’t deny that he had made contact with the victim so willingly gave up the clothing he’d been wearing at the time, and sure enough, all those little palynomorphs indicated that he had been in the woods and not on the lawn. This did not prove that he had committed the crime. It only proved that he had lied about the sequence of events, and that was sufficient to prompt a confession. Otherwise this case would have languished in an eternal hell of ‘he said vs. she said.’

Of course had this guy listened to legal counsel before he made a statement, he probably would have figured out to come up with an alternative, and innocent, reason to have been rolling on the ground near the crime scene, and all these spores would have been for naught. As it is, surely the defense will bring out statistics regarding the vast number of beech and sycamore trees in the area, perhaps in the suspect’s own neighborhood, and the idea that maybe he had been doing some gardening earlier in the week in that same pair of pants. This is why things like pollen analysis fell out of favor with the courts…but the spores are still out there, voluminous, distinct and quite concrete little buggers that will stick in all sorts of places one might wish they wouldn’t. So are hairs, fibers, and paint. Maybe ‘consistent with’ is all you can get out of them. But maybe, sometimes, that’s enough.

So in my books Maggie still looks at all this stuff because it’s more visible and visceral than yet one more DNA sample. Let’s face it—you’ve seen one cotton swab, you’ve seen them all. Bright clothing fibers are much more entertaining.

And this trace evidence will lead her down a number of roads—some of which, it turns out, she’d be better off avoiding.

Wiltshire et al. “A Rapid and Efficient Method for Evaluation of Suspect Testimony: Palynological Screening.” Journal of Forensic Sciences, Vol. 60, #6, Nov 2015, pp 1441-1450.

 

L Black

Lisa Black has spent over 20 years in forensic science, first at the coroner’s office in Cleveland Ohio and now as a certified latent print examiner and CSI at a Florida police dept. Her books have been translated into 6 languages, one reached the NYT Bestseller’s List and one has been optioned for film and a possible TV series.

Lisa’s Website: http://www.lisa-black.com

 

that darkness cover

 

Hello! Just a quick note to let you know that my new book, That Darkness, is now available wherever books are sold!

It seemed like a typical week for crime scene specialist Maggie Gardiner–a gang boss shot in an alley, a lost girl draped over an ancient grave, a human trafficker dumped in the river–nothing all that out of the ordinary for the Cleveland police department as spring turns toward summer along the Erie banks. The methods are usual, the victims unsurprising–but when she notices a pattern, a tenuous similarity among the cases, she begins to realize that her days will never be typical again. How much of her life, her career, her friends, will she be willing to risk to do what’s right?

Jack Renner is a killer who does not kill for any of the conventional reasons…no mania, no personal demons. He simply wants to make the world a safer place. He doesn’t think of himself as a dangerous person–but he can’t let anyone stop him. Not even someone as well-meaning as Maggie Gardiner.

Maggie has the self-sufficiency of a born bit-of-a-loner. She works with a bevy of clever experts surrounded by armed police officers. She is both street smart and book smart, having seen the worst the city has to offer.

But Maggie Gardiner is not safe. And, until she can draw Jack Renner into the light, neither is anyone else.

Jeff Lindsay, author of the Dexter series, says: “Lisa Black always delivers authentic characters in riveting stories. That Darkness takes things to a spellbinding new level with a taut and haunting story that will stay with you long after you finish reading it.”

Publisher’s Weekly says: “The intriguing forensic details help drive the plot to its satisfying conclusion.”

“Black is one of the best writers of the world of forensics, and her latest introduces Maggie Gardiner, who works for the Cleveland Police Department. Her relentless pursuit of answers in a dark world of violence is both inspiring and riveting. Readers who enjoy insight into a world from an expert in the field should look no further than Black. Although Cornwell is better known, Black deserves more attention for her skillful writing – and hopefully this will be her breakout book.”– RT Book Reviews, 4 Stars (Top Pick)

 

Crime and Science Radio: Things That Go Boom in the Night: An Interview with Weapons and Explosives Expert and Author John Gilstrap

High Resolution Author Photo

BIO: John Gilstrap is the New York Times bestselling author of Friendly Fire, Nick of Time, Against All Enemies, End Game, Soft Targets, High Treason, Damage Control, Threat Warning, Hostage Zero, No Mercy, Nathan’s Run, At All Costs, Even Steven, Scott Free and Six Minutes to Freedom.  Four of his books have been purchased or optioned for the Big Screen.  In addition, John has written four screenplays for Hollywood, adapting the works of Nelson DeMille, Norman McLean and Thomas Harris.  He will co-produce the film adaptation of his book, Six Minutes to Freedom, which should begin filming in the spring of 2016 for a 2017 release.

A frequent speaker at literary events, John also teaches seminars on suspense writing techniques at a wide variety of venues, from local libraries to The Smithsonian Institution.  Outside of his writing life, John is a renowned safety expert with extensive knowledge of explosives, weapons systems, hazardous materials, and fire behavior.  John lives in Fairfax, VA.

LISTEN: http://www.blogtalkradio.com/suspensemagazine/2016/03/09/crime-and-science-radio-with-special-guest-bestselling-author-john-gilstrap

Link goes live Saturday 4-23-16 at 10 a.m. Pacific

LINKS:

John’s Website: http://www.johngilstrap.com

Weapons Resource: http://www.nssf.org/newsroom/writers/guide/ (a great 40,000-foot resource for writers who write about weapons)

Weapons Used in Movies: http://www.imfdb.org/index.php/Category:Movie (This site allows you to pull up a movie title and see all of the weapons used.)

 

Friendly Fire

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The Cyber Exchange Principle

Dr. Edmond Locard

Dr. Edmond Locard

 

The cornerstone of forensic science is known as the Locard Exchange Principle. Edmond Locard (1877-1966) studied and developed his investigative skills under the great forensic pioneer Alexandre Lacassagne and later headed the forensic laboratory in Lyon, France. His observations led him to conclude that criminals always left traces of themselves at crime scenes. And took evidence away when they departed. This became the foundation of his exchange principle.

 

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FROM FORENSICS FOR DUMMIES, 2nd EDITION:

The Cornerstone of Forensic Science: Locard’s Exchange Principle

Every contact you make with another person, place, or object results in an exchange of physical materials. If you own a pet, this material exchange is well known to you. Look at your clothes and you’re likely to see cat or dog hair clinging to the fabric—a pain in the behind if you want to keep your clothes looking sharp, but an incredible boon for forensic science. You may also find that you transfer these hairs to your car, your office, and any other place you frequent.

Known as the Locard Exchange Principle, after Dr. Edmond Locard, the French police officer who first noticed it, the exchange of materials is the basis of modern forensic investigation. Using this principle, forensic scientists can determine where a suspect has been by analyzing trace evidence (any small piece of evidence), such as fibers on clothing, hair in a car, or gunk on the soles of shoes.

Looking at Locard’s principle in action:

As an example, say that you have two children and a cat. You run out to take care of some errands that include stopping at a furniture store, the laundry, and the house of a friend who has one child and a dog. From a forensic science standpoint, this sequence of events can provide a gold mine of information.

You leave behind a little bit of yourself at each stop, including

* Hair from yourself, your children, and your cat

* Fibers from your clothing and the carpets and furniture in your home and

car

* Fingerprints and shoe prints

* Dirt and plant matter from your shoes

* Biological materials, if you accidentally cut yourself and leave a drop of

blood on the floor or sneeze into a tissue and then drop it in a trash can

But that’s not all. You also pick up similar materials everywhere you go:

* Fibers from each sofa or chair you sat on at the furniture store ride away

on your clothes, as do hair and fibers left behind by customers who sat

there before you.

* Fibers of all types flow through the air and ventilation system and settle on

each customer at the laundry.

* Hair from your friend, her child, and her dog latch on to you as do fibers

from your friend’s carpet and furniture.

* Fibers, hairs, dirt, dust, plant material, and gravel are collected by your

shoes and pants everywhere you set foot.

In short, by merely running errands, you become a walking trace evidence

factory.

Today, many crimes have at least some cyber component—cell phones, computers, e mails. text messages, etc. Does the cyber world also have such a cyber exchange principle? Yes it does and it’s actually quite extensive.

Forensic Magazine article: http://www.forensicmag.com/articles/2011/12/digital-forensics-cyber-exchange-principle#.UtFmzHn4VTE

 
2 Comments

Posted by on April 12, 2016 in Uncategorized

 

Crime and Science Radio: Building a Better Law Enforcement: An Interview with Chief Scott LaChasse, Burbank Police Department

SLaChasse

 

BIO: Scott LaChasse has 36 years of experience in law enforcement and security. He joined the Burbank Police Department as Interim Chief in January, 2010 and was named permanent Chief in April, 2013.  Chief LaChasse worked for the Los Angeles Police Department from 1970-2002, most recently holding the position of Deputy Chief. In this capacity, he managed almost 1,600 personnel in South Los Angeles.

During his tenure at the LAPD, he held a variety of high-profile positions including Commanding Officer for the Criminal Intelligence, Narcotics, and Uniformed Services Groups. He also served as Assistant Commanding Officer of Operations for the Valley Bureau where he administered the activities of 1,800 personnel in the San Fernando Valley.

His resume includes work as the Vice President of Security and Emergency Services for Paramount Pictures and Corporate Manager for Regulatory Compliance at Southern California Edison.

Chief LaChasse is a member of several organizations including the International Association of Chiefs of Police, FBI National Academy Associates, California Peace Officers Association, William H. Parker Los Angeles Police Foundation, Chief Special Agents Association, California Police Chiefs Association, Challengers Boys and Girls Club Board of Directors, Peace Officers Association of Los Angeles County Executive Board, and Los Angeles Police Museum Board of Directors. He also provides instruction nationally and internationally to public officials and law enforcement officers on the command of critical incidents.

Chief LaChasse earned his Bachelor’s degree from California State University, Los Angeles, and his Master’s in Public Administration from The University of Southern California. A longtime supporter of forensic science in Los Angeles County, he is on the Advisory Board of the California Forensic Science Institute at CSULA and is honored in the CSFI Hall of Fame for his work on behalf of forensic science research, training, and education.

LISTEN: http://www.blogtalkradio.com/suspensemagazine/2016/03/01/crime-and-science-radio-with-special-guest-scott-lachasse

Link Goes Live Saturday 4-9-16 at 10 a.m. Pacific

LINKS:

LAPD: http://www.lapdonline.org

LAPD Organization Chart: http://www.lapdonline.org/inside_the_lapd/content_basic_view/1063

Burbank Police Department: http://www.burbankpd.org

City of Burbank: http://www.burbankca.gov

International Association of Chiefs of Police: http://www.iacp.org

California Police Chiefs Association: http://www.californiapolicechiefs.org

California Forensic Science Institute: http://www.calstatela.edu/hhs/cfsi

Fact Sheet: Justice Department Counter-Terrorism Efforts Since 9/11: https://www.justice.gov/archive/opa/pr/2008/September/08-nsd-807.html

 

2016 ITW Thriller Awards Nominees

 

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2016 ITW Thriller Awards Nominees 

 

We’re thrilled to announce the finalists for the 2016 ITW Thriller Awards:

 

BEST HARDCOVER NOVEL

Ian Caldwell – THE FIFTH GOSPEL (Simon & Schuster)

Tess Gerritsen – PLAYING WITH FIRE (Ballantine)

Paula Hawkins – THE GIRL ON THE TRAIN (Riverhead Books)

David Morrell – INSPECTOR OF THE DEAD (Mulholland Books)

Karin Slaughter – PRETTY GIRLS (William Morrow)

 

BEST FIRST NOVEL

Sandra Block – LITTLE BLACK LIES (Grand Central)

LS Hawker – THE DROWNING GAME (Witness Impulse)

Gilly Macmillan – WHAT SHE KNEW (William Morrow)

Brian Panowich – BULL MOUNTAIN (G.P. Putnam’s Sons)

Hester Young – THE GATES OF EVANGELINE (G.P. Putnam’s Sons)

 

BEST PAPERBACK ORIGINAL NOVEL

Marc Cameron – DAY ZERO (Pinnacle)

John Gilstrap – AGAINST ALL ENEMIES (Pinnacle)

Andrew Mayne – NAME OF THE DEVIL (Bourbon Street Books)

D.J. McIntosh – THE ANGEL OF EDEN (Penguin Canada)

Jean Rabe – POCKETS OF DARKNESS (WordFire Press)

 

BEST SHORT STORY

Reed Farrel Coleman – “Feeding the Crocodile” JEWISH NOIR (PM Press)

Jeffrey Deaver – “Repressed” (Diversion Books)

Sharon Hunt – “The Water Was Rising” (Ellery Queen’s Mystery Magazine)

Terrence McCauley – “El Cambalache” (Thuglit)

Joyce Carol Oates – “Gun Accident: An Investigation” (Ellery Queen’s Mystery Magazine)

 

BEST YOUNG ADULT NOVEL

Alan Gratz – CODE OF HONOR (Scholastic Press)

Nicole Maggi – THE FORGETTING (Sourcebooks Fire)

Michelle Painchaud – PRETENDING TO BE ERICA (Viking Books for Young Readers)

Emily Ross – HALF IN LOVE WITH DEATH (Merit Press)

Allan Stratton – THE DOGS (Sourcebooks Fire)

 

BEST E-BOOK ORIGINAL NOVEL

Diane Capri – JACK AND JOE (AugustBooks)

Chris Kuzneski – THE PRISONER’S GOLD (Chris Kuzneski)

Robert McClure – DEADLY LULLABY (Alibi)

Caitlin O’Connell – IVORY GHOSTS (Alibi)

Eric Rickstad – LIE IN WAIT (Witness Impulse)

 

Congratulations to all the finalists!

The 2016 ITW Thriller Award Winners will be announced at ThrillerFest XI, July 9, 2016, at the Grand Hyatt (New York City.)

Very special thanks to:

Joshua Corin, Awards Committee Chair

Jennifer Kreischer, Awards Coordinator

Suzanne Rorhus, Awards Coordinator

And all the 2016 ITW Thriller Awards Judges

Carla Buckley

ITW Board of Directors, Vice President, Awards

 
1 Comment

Posted by on April 5, 2016 in Writing

 

Q and A: Can A Blow To the Head Cause Unconsciousness and Amnesia?

Q: How hard do you have to be hit on the head to be knocked unconscious? Is there a particular place on the head, that if struck would be more likely to cause unconsciousness? How long does it usually last? How hard do you need to be hit to cause partial or temporary amnesia? What sort of things do people forget in these situations? How long does it usually last? Are there any other physical symptoms a writer should be sure and include in a scene with head trauma?

amnesia

 

A: In medical terms a blow to the head, or anywhere else, is called blunt force trauma as opposed to sharp force trauma as would occur with a knife or some other cutting instrument. When the blow is to the head, it is called a blunt head injury.

The degree of force required to render someone unconscious is completely unpredictable and varies from situation to situation and from person to person. Though a minor tap on the head is not likely to cause unconsciousness in anyone, almost any blow of significant force can. It makes no difference where the blow strikes the head as far as causing unconsciousness is concerned. That is, a blow to the front of the head is no more likely or less likely to cause unconsciousness than would one to the side or back of the head.

The period of unconsciousness in a simple concussion, which is what loss of consciousness due to blunt force head injury is called, is measured in seconds or minutes. Unlike Hollywood where the bad guy is slugged in the jaw, knocked unconscious, and then written out of the script after that — or at least the hero no longer has to worry about him — is not what happens in real life. Think about every boxing match you’ve ever seen. One guy smacks the other one, knocking him unconscious, and 30 seconds later the guy is awake and complaining that it was a lucky punch. This is what really happens.

Unconsciousness from a simple concussion can last several minutes and maybe even up to 10 or 15 minutes, though that would be unusual. Typically the person wakes up with a minute or so but might be slightly groggy or confused for a while, again for several minutes. But if he is unconscious for longer than a few minutes, the odds are that a serious injury to the brain has occurred or that bleeding into and around the brain has happened, Both of these situation are true medical emergencies. It doesn’t sound like that’s the situation you are posing with your questions.

Amnesia can indeed follow blows to the head. Typically the blow has to be powerful enough to render the person unconscious or at least woozy before amnesia enters the picture. But I should point out that other than the time period the victim is actually unconscious there is no loss of memory in the overwhelming majority of people who suffer head injuries. Amnesia is not rare but it is not common. But amnesia can occur after head injury, so you can absolutely use this in your story.

Amnesia is an extremely odd and actually not well understood medical condition that comes in many flavors and types. For easy explanation, amnesia is often divided into retrograde and anterograde types. Anterograde amnesia is very rare and is a situation where the person cannot form new memories. This was the subject of the excellent movie Memento. I won’t dwell on this since this is not the type of amnesia your questions deal with.

 

Memento

 

Retrograde simply means whatever came before. This type of amnesia is the most common in that the person forgets things that happened before the injury. This amnesia can cover events that occurred for only a few minutes before the injury, a few hours, a few days, weeks, or months, or can go back to forever. The person can forget some things and not others, such as he might not remember his name but might remember his address and phone number. He might remember some people but not others. He might recognize people but not be able to recall their names.

Or he could have what is called global amnesia in which he remembers nothing, not his name, not where he is, not where he came from, and virtually everything else. This type of amnesia can be temporary or permanent. It may only last for a few minutes, hours, days, or months or in some people it can last forever and be a permanent loss of memories.

When memories begin to return, they can come back suddenly and completely, partially, or in fits and spurts. The person might remember some things within a few minutes but other things might be lost in the cloud of amnesia forever. Virtually anything can happen so this means that your story can be crafted in almost any way you wish.

The other symptoms that can be associated with a concussion of this type are headaches, dizziness, poor balance, nausea, blurred vision, and generalized weakness and fatigue. These symptoms usually are minor and only last a few hours but they can become more problematic and last for many days and in some people for many months. There is no real treatment other than time and perhaps medications for headaches if they become chronic.

 
3 Comments

Posted by on April 5, 2016 in Medical Issues, Trauma

 
 
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