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Monthly Archives: March 2016

Guest Blogger: Megan Inslee: My Love-Hate Relationship with Forensic DNA

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What is the most important point to keep in mind when working with forensic DNA evidence?  There are probably a lot of answers to that question, depending on your experience and perspective.  I’ll let you in on my opinion for now, as a former DNA forensic scientist. One of the imperatives of working forensic DNA cases in this modern age is this: accepting that there are cases (many, in fact) that DNA can’t resolve.

Almost every time I testify, I’m asked “why might you not find DNA?” This is a good question, one which I usually answer with a fairly long list of possibilities, but it all boils down to three main points. 1. DNA may not have been deposited in the first place. Does this mean that the incident didn’t happen as reported by the victim or witnesses? Not necessarily – more on that a bit later.   2. Maybe too little DNA was deposited for the lab to test and identify. But can’t you guys detect even a few cells? More on that, later, too.  Or, 3. Perhaps DNA was deposited at an adequate level, but much of it was washed away or degraded over time. I saw a special on cold cases solved by DNA decades later – I don’t believe there’s anything you can’t do. Well, keep reading.

1. DNA may not have been deposited in the first place.

We’ve become so accustomed to DNA evidence being presented in criminal justice cases that we seem to need to take a collective step back to reflect on a case in which it just isn’t there.  It really depends on the scenario and the knowns of the case what this lack of DNA on an evidence item could mean.

The murderer doesn’t always cut herself on the knife and leave drops of her blood at the scene. The burglar may have kept his gloves on throughout the entire crime, never touching anything with a bare hand.  A child molester doesn’t always leave semen evidence for us to test.

And, of course, DNA may not be present on a tested evidence item simply because the scenario didn’t unfold the way investigators believed or the witnesses stated or the victim recalled.  Corroborating DNA evidence with reported scenarios is a tricky business, one which doesn’t always result in a resolution tied up with a big red bow.

2. Maybe too little DNA was deposited for the lab to test and identify.

Remember the days when crime labs couldn’t get DNA from anything smaller than a blood drop the size of a quarter?  And remember when, even when they started getting DNA from smaller samples, the odds of someone else having the same DNA profile was only one in several thousand?  Well, I don’t – that was before my time.

But I was there for the early years of the current DNA typing technology, Short Tandem Repeats (STRs). Those were the days in which we tested mainly blood, semen, and saliva.  We had a good idea of what we could and couldn’t get results from and we ended up with a lot of single-source DNA profiles.  These result in straight forward comparisons to reference samples which yield either an exclusion, if the profiles don’t match, or a match.  In the case of a match, we calculate and issue some crazy-big statistic that illustrates to the reader (the investigator or attorney or juror) just how significant this match is (spoiler alert: the number is often in the quadrillions – matches are pretty darn significant).  And as great as this is and was, the criminal justice system wanted (and in many cases, needed) more.

Science over time, I’ve found, rarely disappoints.  The techniques and products that result from years of experimentation, trial and error, grant funding and academic research end up being a culmination of the best approach among many.

Instead of changing the sites we used for forensic DNA typing, researchers found that we could extract and clean up the DNA a little better and attain higher sensitivity.  They modified the primers and added a few more.  They improved the reagents that we used to get our profiles and made them a little more robust. They made instruments that could automate sample processing so that we could do more samples in less time.  All of this has led to higher throughput and more sensitive results.

Currently, scientists are not just attempting to get DNA profiles from well-defined body fluid stains, as before, but also from areas of evidence items that have tested faintly positive for a body fluid. They are swabbing areas of items that someone in the case may have touched.  These types of samples have much, much fewer cells than, say, a fat drop of blood.  And, while significant to the case and incident at hand, these samples are likely to contain not only very few cells, but mixtures of more than one person’s DNA, further complicating the analysis.

3. Perhaps DNA was deposited at an adequate level, but much of it was washed away or degraded over time. 

It’s important to remember that DNA is a molecule, one with millions of parts.  Cells must be intact in order to properly preserve the DNA.  And hundreds of cells must be present in a sample in order to obtain a decent profile for comparison. Wiping or washing a surface can remove cells. Environmental factors such as heat, UV light, or bacteria can break cells open, exposing DNA and ultimately breaking it down.

Also, it’s useful to know that the laboratory process, itself, is lengthy, requiring many phases, none of which perfectly preserve all of the DNA in the sample from one step to the next.  If I detect 200 cells in a sample in the lab, it doesn’t mean that 200 cells were originally deposited on the evidence item at the time of the crime.  Even in the best evidence-preservation scenario, there is loss of genetic material on the crime-scene-through-laboratory-testing journey.

In the end, as much as I love forensic DNA (and I hope you do, too), it’s important to keep its limitations in perspective in every case. The presence of DNA evidence does not prove guilt. The absence of DNA evidence does not prove innocence. The current state of forensic DNA technology is, however, amazing! I think we can all relish in that without abandoning our role as critical thinkers.

MInslee

Megan Inslee spent 13 years as a DNA forensic scientist in Washington State.  She has her Bachelor’s in Biology as well as her Master’s in the Genetics track of Laboratory Medicine from the University of Washington. She currently resides on an island outside of Seattle with her husband and three small children, writing technical documents, preparing grant proposals, and providing consultation on a freelance basis.

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Posted by on March 29, 2016 in DNA, Guest Blogger, Uncategorized

 

Crime and Science Radio: Research, Education, and the Future of Forensic Science: an Interview with Dr. Katherine A. Roberts, Director of the CSULA Graduate Program in Criminalistics

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Research, Education, and the Future of Forensic Science: an Interview with Dr. Katherine A. Roberts, Director of the CSULA Graduate Program in Criminalistics

 

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BIO: Dr. Roberts is the Director of the California State University, Los Angeles Graduate Program in Criminalistics. She has served as the Director of the Master of Science degree program there since 2002,and played a leading role in the university’s FEPAC accreditation. Her research interests cover a wide array of forensic disciplines, but focus primarily of trace evidence analysis, sexual assault evidence, and mitochondrial DNA analysis. Dr. Roberts was the PI of a National Institute of Justice-funded study to investigate the use of samplematrix™ to stabilize crime scene biological samples for optimized analysis and room temperature storage from 2009-2011. She is the PI for a National Science Foundation grant that was awarded to CSULA in 2015 to establish the Center for Interdisciplinary Forensic Science Research as a research site within the NSF Industry-University Cooperative Research Center (I/UCRC) program. The Center will enhance research training and education in multiple forensic science disciplines, including Forensic Microscopy, Trace Evidence Analysis, Forensic Science Research Methods, Forensic Chemistry, and Applications of Forensic Science.

Dr. Roberts is currently collaborating with a consortium of European universities to develop a portable, inexpensive, and rapid method of dating latent fingerprints. Her publications are on topics related to trace evidence analysis, forensic examination of sexual assault evidence, and mitochondrial DNA analysis.

She was an elected member of the Technical Working Group for Education and Training in Forensic Science (TWGED) that was convened by the National Institute of Justice. The Forensic Science Education Programs Accreditation Commission (FEPAC) uses the report issued by TWGED in order to evaluate the academic standards of undergraduate and graduate forensic science programs.

Dr. Roberts is currently serving as the  Interim Executive Director of the California Forensic Science Institute.

Education

PhD     Forensic Science, Graduate School & University

Center, City University New York

M.Phil  Criminal Justice, Graduate School & University

Center, City University New York

MSc     Forensic Science, University of Strathclyde, Glasgow

BSc     Chemistry, King’s College, University of London

 

LISTEN: Link Goes Live Saturday 3-26-16 10 a.m. Pacific http://www.blogtalkradio.com/suspensemagazine/2016/02/23/crime-and-science-radio-with-special-guest-dr-katherine-roberts

 

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

CSULA School of Criminal Justice and Criminalistics http://www.calstatela.edu/hhs/crim

LA Times article, “Cal State L.A. graduate students hone crime scene expertise,” http://articles.latimes.com/2013/jul/27/local/la-me-cal-state-criminalists-20130728

Forensic Science Education Programs Accreditation Commission (FEPAC) http://www.fepac-edu.org

 

ThrillerFest/CraftFest/Master CraftFest are coming July 5-9, 2016

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ThrillerFest is the premiere conference for thriller enthusiasts, bringing together fans, famous authors and new ones, industry professionals and agents. It’s a vibrant hub of literary networking and social interaction offering an opportunity for thriller lovers to meet and mingle with their favorite authors at the Grand Hyatt Hotel in New York City every July. When we say mingle, we mean it. An array of impressive names, including Clive Cussler, Lee Child, James Patterson, Sandra Brown, Harlan Coben, David Baldacci, David Morrell, Ken Follett, R.L. Stine, and many more have been known to linger in the conference rooms and halls, accessible to attendees.

The ThrillerFest team is busy preparing for a memorable 2016 conference, hoping to make it the best yet. The conference consists of several events, priced separately and in money-saving packages. Those events are:

Today’s FBI: Crime Essentials For Writers

In this full day workshop held at FBI Headquarters, you’ll hear from FBI experts in Cybercrime, International Terrorism, Criminal Investigations, and more. Lunch, drinks, and snacks served. Class size is limited by the FBI and fills up quickly.

Master CraftFest

Don’t miss this opportunity to study with the Masters of the genre in a one-day intensive workshop to take your writing to the next level. Everyone is welcome, from beginning writers to well-established authors. The instructors this year will be Steve Berry, Grant Blackwood, David Corbett, Meg Gardiner, Heather Graham, Andrew Gross, Richard Krevolin, and Gayle Lynds. Class sizes are limited to provide a personal experience.

CraftFest

As always we have a group of talented teachers to broaden your knowledge about the craft of writing as well as experts in many fields like forensics and firearms so you can get the facts right in your novel.

PitchFest

Be sure to sign up for the incredible opportunity to further your writing career, as we’ll have over 50 agents, editors, and producers ready to hear your pitch at our annual PitchFest event. Visit www.thrillerfest.com and read the Success Stories from past years.

ThrillerFest

We’re planning some phenomenal panels, always trying to innovate and entertain. Join us for the spotlight interviews, cocktail parties, workshops, and fabulous networking opportunities. Please check the volunteer box during registration, as it’s a great way to make new friends.

Thriller Awards Banquet
A gala banquet and celebration tops off everything, with 2016 ThrillerMaster Heather Graham receiving her award, and the exciting announcement of the winners of the Thriller Awards!

Exhibitor/Vendor Tables
We’re offering exhibitor/vendor tables during the ThrillerFest event for non-bookselling vendors. If you’d like to promote your goods, services, or brand, it’s an excellent opportunity to reach many thriller enthusiasts.

Enter the Best First Sentence Contest for a chance to win a critique of 10 manuscript pages from one of our phenomenal Master CraftFest teachers.

More Info and Registration: http://thrillerfest.com

Follow us:

Facebook: https://www.facebook.com/International-Thriller-Writers-Organization-59208702261/

Twitter: https://twitter.com/thrillerwriters

Hope to see you all in New York

DP Lyle
ITW VP for Education
CraftFest/Master CraftFest/Thriller School Director

 
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Posted by on March 21, 2016 in Writing

 

Diatoms: Microscopic Clues of Death By Drowning?

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DIATOMS

What are diatoms? How do they help the Medical Examiner determine that a death was from drowning?

Determining that someone has drowned is not as easy as it might seem. The finding of water in the lungs isn’t enough. Sure drowning victims most often have water-filled lungs but if a corpse is tossed into a body of water, the lungs will often passively fill as the water replaces the trapped air in the airways and lung tissue. However, if the ME finds inhaled debris such as plant and water-born insects, etc. deep in the lungs, this suggests that the victim was breathing at the time they entered the water and inhaled the debris-filled water. But this isn’t always found.

So a method for determining drowning is needed. Diatoms might help. Though controversial and definitely not universally accepted as a sign of drowning, this search for diatoms is an interesting forensic science technique. And this search is not in the lungs, but rather in the bone marrow.

From HOWDUNNIT: FORENSICS:

The ME might also find clues to indicate that the victim was conscious before drowning by examination of the bone marrow. This might sound odd at first, but the key is in finding tiny creatures called diatoms within the marrow.

Diatoms are tiny single-celled organisms that scurry around in both salt and fresh water. They have silica in their cell walls and are very resistant to degradation. If the victim’s heart is still beating when he enters the water, any diatoms in the inhaled water will pass through the lungs, enter the bloodstream, and be pumped throughout the body, where they tend to collect in the bone marrow.

If a microscopic analysis of the marrow reveals diatoms, the victim must have been alive at the time of water entry. This technique may be useful in severely degraded or skeletal remains where no lungs or sinus tissues are available for examination. Unfortunately, diatom testing is not exactly that straightforward and is controversial. Some experts feel that diatoms are an inexact tool for determining if a drowning occurred. Some bodies of water contain no diatoms.

Also, they are found in air and soil and even on the clothing of the examiner. This makes contamination of the tested sample a possibility.

 

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Dirty DNA

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One truth in forensic DNA testing is that you must have a sample to test. That, of course, should be self-evident. But sometimes crime scene DNA isn’t readily available. There are no blood or semen stains on the floor or bed sheets or any location where they could be easily sampled. What’s the crime lab to do?

New methods are under development that allow for extracting useable DNA from some unusual places, even dirt. GEMBE (gradient elution moving boundary electrophoresis) grabs DNA hidden in the dirt by employing a molecular “tug-of-war.” Cool.

For more about DNA sampling and testing, grab a copy of my updated, 2nd Edition of FORENSICS FOR DUMMIES.

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INFO/PURCHASE

 
 
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