Showing posts with label DNA profiling. Show all posts
Showing posts with label DNA profiling. Show all posts

Sunday, October 26, 2014

Familial DNA: An Unusual Way for Your Inspector to Find the Perp - Information for Writers


__________________

I was recently chatting with David Swykert about some of the stories he'd come across while at work as a 9-1-1 operator. He introduced me to a new concept, familial DNA.

First, David, would you please introduce yourself?


David - 
I am a retired 911 operator living in northern Kentucky. I also worked as an operations manager for a large transportation company and as part of my job investigated accidents. I worked as an emergency operator for the Department of Public Safety in northern Michigan until 2006. I have written in several different genres, mystery, romance, and even some literary, short fiction and novels. I have five published novels.

Fiona - 
How did you first learn about familial DNA in crime cases?

David - 
I first heard about Familial DNA from the officer that was our CSI for our department. It's simply a DNA search that turns up no exact match, so you ask the computer for the closest match.

Fiona -
If you need a quick brush up on DNA in crime scenes go HERE

So the DNA found at a scene that did not match any of the DNA that was in the computer bank. The officer would then task the computer to find as close a match as possible, hoping to find the general family from which the possible perpetrator belonged. Is there precedent for this?

David - Yes. Lonnie David Franklin, deemed The Grim Sleeper, because of the length of time in between murders committed by him. There was never any DNA at any of the crime scenes that identified Franklin. 

The investigators found him by running a Familial DNA search which turned up his son, who was a convicted felon. This led the investigators to Franklin. 

After Franklin's arrest, the investigators tested Franklin and his DNA was a match with that found at the crime scene. 

He was caught the summer of 2009. But this case is just going to trial perhaps this year (2014). There have been volumes of appeals and briefs filed because there was never any direct evidence that connected Franklin to the crimes, and defense lawyers contend his investigation based on someone else DNA was a violation of his Fourth Amendment rights concerning illegal search and seizures.


The argument is: the inspectors had no direct evidence that connected Franklin to the crime before they investigated him.

When you run a persons records, you have to have a law enforcement purpose that allows the search, the defense contended they didn't have one. 

The courts have ruled so far in favor of the prosecution, and the trial is moving forward. But it will get appealed to higher courts. The Fourth Amendment protects you against unusual search and seizure, but of course there can be very broad interpretations of what this means.

Fiona - 
What are the arguments against using familial DNA?

David - 
Civil Libertarians argue that using someone else's DNA to justify investigating someone else violates the Fourth Amendment that protects us against "unreasonable" search and seizure. They see this as "unreasonable." 

I really don't think an officer can "abuse" the technique. In defense, the lawyers can always ask to see who's DNA caused the detectives to investigate a defendant, discover whether that DNA close to the perpetrators, and ask about probable cause. 

Amazon Link
When I heard about familial DNA searches, I thought it would be a great hook for a crime story, which I wrote in early 2009 just before LAPD caught The Grim Sleeper using the technique.

I'm surprised crime writers haven't written a lot of books regarding the use of the technique. In mine, they catch him, but the D.A. isn't sure they can prosecute him successfully, which causes my detective, Bonnie, a lot of consternation. She knows he did it, but perhaps he can't be convicted. Which could happen out in LA. That's just getting started.
Fiona - 
Let's talk about your book. Can you give a synopsis?

David - 
This is a fictional story about Detroit Homicide Detective Bonnie Benham, who convinces the District Attorney to allow a Familial DNA search as she investigates the murder of several young girls. 

The book reveals standard investigative homicide procedures and the frustration of the officers as all leads go nowhere and the body count continues to mount. A task force is put together and Bonnie and her partner, Neil Jensen, who understands Bonnie’s frustration, become inseparable as they track this killer of children.

Fiona - 
I had never heard of familial DNA prior to your book, while it will probably be more prominent as the trials catch the imagination of writers. If a writer wants to include this twist in their plot line can you give us any more information about the process?

David - 
It's no different than a DNA search, except the lab expands the search to include DNA that is close to the DNA profile from the crime scene. The investigators then investigate the people the expanded search includes. 

Last time I checked there were only two states in the U.S. that even have a policy regarding it's use, Colorado, and California, Michigan, where my story is set, is not one of them. 

What I thought would be the hook for my story is the old: I know he did it, but I can't prove it. It took from 2009 until this year for the courts to get The Grim Sleeper into a courtroom, and this case will perhaps set precedence for the future use of the technique. I think the rest of the states are waiting to see the outcome before they write a policy.

Fiona -
What do you hope the outcome will be?

David - 
I want to see the guilty convicted. DNA profiling has worked both ways, it's freed a lot of innocent people. As unique as DNA is, I would hope the courts decide if the DNA is close enough to a match this constitutes a reasonable search. 

I'm not an expert on the scientific profiling of DNA, but I would think they can set parameters that the profile must meet, a standard, which when met, allows indicates that it is reasonable to investigate this person. 

I believe ultimately the courts will allow its use. Fingerprinting isn't absolute, and they allow it entered as evidence. So there is already precedence.

Fiona - 
David, thank you so much for chatting with us today - I can almost hear all of the cogs starting to 
whir in the minds of mystery writers.


Thank you so much for stopping by. And thank you for your support. When you buy my books, you make it possible for me to continue to bring you helpful articles and keep ThrillWriting free and accessible to all.



Wednesday, March 19, 2014

Forensic Trace Evidence: Hair and Fur - Info for Writers




CRIME SCENE DO NOT CROSS / @CSI?cafe
 (Photo credit: Wikipedia
So your investigator arrived on the scene.
(Crime Scene 101 for writers article)

They've photographed and collected all of the macro-evidence. 

Now they need the trace evidence (that which isn't easily seen with the naked eye) collected and processed. This trace evidence might include hair. 
* Hair is one of the most collected forms of trace evidence.
* Hair is particularly useful because it is stable over time.
* Because hair is produced around blood vessels it is a long term
   record of toxins
   ` Illicit drugs such as THC in marijuana
   ` Poisonings such as arsonic
   ` Heavy metal exposure such as lead.
   ` Medications
* Hair grows at a fairly predictable rate of about .5 inches per
   month. So scientists can even calculate when the exposure to
   the toxin began - depending on the length of the hair.


Investigators will use three basic means of collecting hair and other trace evidence.

1. Hunt and peck
2. Tape
3. Vacuum
Video Quick Study (9:50) Prt 1 
Video Quick Study (1:54) Prt 2 Teacher explaining collection
                     methods of finding trace evidence including hair. 



Humans have various hair all over their bodies including body hair, eyelashes, and eyebrows. But only head hair and pubic hair have forensic use.


So let's say we have a rape victim. They find hair on her clothes. 
1. They will have to collect hair from the victim - this is a known or
    K sample
2. The laboratory will compare the victim K sample to the 
    Q sample - the sample in question.
    a. First, they will figure out if the Q sample is a human hair.
    b. Second, They will determine if the K and Q samples have
        the same general characteristics.

Let's say that the victim K sample excludes the Q sample that is they could not come from the same person. But our investigators have their eye on a bad-guy. They ask him for hair samples. He can 
a. Agree and submit to testing
b. Refuse - if he refuses then the courts can order him to submit.

The suspect K sample is collected.
1. It is suggested by the FBI that 100 full, intact strands, including
    the follicle are harvested from the suspects head from various
    regions as even hair from an individual person can differ
    from region to region on their heads.
2. It is suggested that at least 20 intact strands of pubic hair are
    obtained.

*If the laboratory says that the suspect K sample and the Q sample
  do not share similar qualities, this excludes the suspect. 
*If the lab says that there are similarities in the K and Q samples,
  this DOES NOT mean that you found your villain. 
* Hair is class evidence - it can be used to exclude but not to prove
   someone is culpable.
* If there are similarities, the sample is sent for DNA testing.
  (DNA 101)
* By doing lab analysis first, it saves a great deal of time and money
   over going right to DNA analysis

Let's do a little biology 101 - I know you're excited!

hair follicle
(Photo credit: Wikipedia)

* The root of the hair is
   anchored into the dermis of
   the skin
* Follicles are surrounded by
   epidermal cells
* Blood vessels at the roots
   deliver nutrients






Looking at the hair itself

* Hair is mostly made
   from keratin
Haarstrukturen im Vergleich
 (Photo credit: Wikipedia)
* The outside of the hair is 
   called the cuticle
* In humans, the cuticle
   gives very little information. 
* Mammals have various
   patterns in their cuticles and
   the labs can compare the
   various patterns to tell
   that's a bat, or a rabbit, or a
   werewolf. 

* Inside of the cuticle is the cortex.
* The cortex is the thickest layer of the hair strand.
* This is where pigment from the melanin can be found, giving hair
    its color.
   ` Hair colorant can coat the surface or penetrate to the cortex.
   `In bleached hair pigmentation is lost from the cortex
   `Only the hair that is treated will show a change in color, so at the
     root the true color will be visible. There will be a line of 
     demarcation between the two

* When people change the color of their hair, or their hair changes
    naturally as the subject ages, this can create issues in finding 
    similarities in the K and Q samples. 
* PLOT TWIST!
   A fingerprint cannot be altered, but your villain can thwart an
   investigator by dying their hair, committing a crime,
   and then dying their hair a different color. So even if the police
   take K samples from their hairbrush they will not show as similar
   in the lab. And when they take them from hair that's been altered
   it too will not show as the same.



Photomicrograph of Pubic Hair Medulla
Pubic Hair Medulla (Photo credit: Wikipedia)
The Medulla
* The medulla is at the core of the hair sample
* It is the hollow region at the center.
* A data bases of medulla patterns have been developed to
   identify various animals and differentiate human from other
   animal hair.
* Finding animal hair can be very helpful. It can link transferred
   hair from a suspect at a crime scene. For example, Blade Slayer
   goes in and attacks your heroine. Trace evidence hair is found.
   It's a black rabbit, and Blade Slayer happens to have a black
   rabbit named Cuddles. It's circumstantial, but it can be helpful.
* Animal hair forensics can also be used in crimes like poaching
   and illegal animal importation (Wildlife Forensics Blog Post)


Three Phases of Hair Growth

Anagen Phase
* 2-7 yrs for scalp hair 
* Growth phase where cells are formed at the root which pushes the
   hair out of the scalp making the hair longer.
* This hair will only fall out if it is yanked out.
* When hair from this phase is
Animation of the structure of a section of DNA...
Animation of the structure of a section of DNA. The bases lie horizontally between the two spiraling strands. (Photo credit: Wikipedia)
   found at the crime scene it has a
   follicle attached. 
* The follicle contains DNA that
   will identify an individual
Catagen Phase
* The hair is in transition
* The hair no longer grows, the
   cuticle pulls away
Telegen Phase
* The final phase where hair falls
   out.
* In the catagen and telegen
   phases the follicle is no longer
   attached to the hair. Nuclear
   DNA cannot be found. The
   investigators will try to test for
   mitochondrial DNA in the hair
   shaft. Mitochondrial DNA is not
   conclusive as everyone in the
   matriarchal line will have the
   same DNA (DNA 101 for Writers)
* Telogen hairs are those typically found at crime scenes.
* Because hair is easily transferred from one place to another, it is
   circumstantial evidence.

What else can an investigator tell from a hair strand?

* Pubic hairs have shaft differences along the length and a
   continuous medulla
* Male facial hair is usually more triangular in shape
* Hair that's been cut or shaved will have a blunt end
* Hair that is allowed to grow naturally such as arm hair will have a
   naturally tapered end
* Head hair - not recently cut- will show a frayed or split end
* Age cannot be discerned.
* Sex cannot be determined.
* Ethnicity - is difficult. The person would have to have a very
   clean background as Caucasian, African, or Asian ancestry.
   And then, there are variables that can point the investigators
   in a direction. It is not conclusive.



So what can an investigator say about a hair sample?

* Is it human, or animal (or vampire)?
* Is it a useful sample, either head or pubic hair?
* Is it head or is it pubic hair?
* Is the Q sample consistent with the K sample?
   `If yes, further investigation - suspect stays in the pool.
   `If no, suspect is removed from possibilities; they look for another
    suspect.
   `If yes AND no that is there are similarities AND differences,
    then no conclusion can be drawn.

Video Quick Study (4:16) Hair testimony at Casey Anthony trial
Video Quick Study (4:27) Britain CSI school


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