D is for DNA Profiling

photo credit: micahb37 via photopin cc

The days are getting longer and we are getting farther into the Crime Fiction Alphabet meme. If you are unfamiliar with CFA, it is a challenge run by Kerrie over at Mysteries in Paradise, so head on there and sign up, or click on some links and read what others have to say. This is my second time at this dance off  and I have chosen to focus on topics related to crime fiction rather than books and/or authors.

“DNA leads to arrest in 20-year old double murder!” screams the headline, and we know that we can rest safely tonight thanks to the men and women behind DNA and the DNA test. Everyone has heard about DNA and we all know that each person’s DNA is unique (except in the case of identical twins). Most of us know that the DNA strand has a double helix shape and some even know that it is made up of bonds between pairs of nucleotides. But, what exactly is DNA testing and what do all those lines and squiggles mean?

The first thing to realize is that a DNA test doesn’t compare your entire DNA to another DNA. Mapping the order of every nucleotide in DNA, referred to as Genomic Sequencing, is an enormous undertaking and pretty wasteful, since we share 99.9% of our DNA anyway. Instead, DNA testing isolates certain short repeated sequences in the DNA, called Short Tandem Repeats or STRs that are different across the population. Each STR, also called a Marker, has a certain sequence that is repeated where the number of repeats are highly variable across the population but similar within related individuals. For example, one person’s sequence may look like so “GATAGATAGATAGATA.” If you notice carefully, you will see that in this sequence “GATA” is repeated 4 times. For another person, this marker may have 8 repetitions of “GATA” instead of 4 and so on. However, one marker is still not enough to distinguish between two individuals since the chances are still high that any two people could have the same number of repeats within a marker. So, DNA profiling uses a combination of different markers to narrow the possibilities down considerably. The number of markers used varies by country. In the U.S. 13 markers are used to during testing.

DNA profiling can be used for a variety of purposes including identifying victims, paternity tests, and tracing one’s genealogy. The process remains the same though the interpretation changes especially when tracing one’s genealogy since the differences between two strands increases as you move farther up the genetic tree. There is also a lot more to the analysis including a process called PCR (Polymerase Chain Reaction) which is a way of replicating specific portions of a DNA. PCR is obviously very important because it allows the forensic experts to work with the tiniest of DNA samples by using PCR to replicate that tiny bit into an amount sufficient to test on.

Finally, some recent work by an Israeli scientist has shown that it is possible to generate fake DNA evidence (including saliva and blood samples) using the information about marker information found in a DNA database. The good news is that they have also created a test that can be used to determine if the DNA has been artificially generated. The bad news is that it is unknown if this test is being used in the wider community. Chances are slim since actual cases involving manufactured DNA are not known at this time. However, it will make an interesting plot device for a future crime novel.

So what do all those lines and squiggles mean on a DNA profile (like in the picture in this post)? It is the output of an automatic DNA sequencer and indicates the presence of various marker lengths. A person’s profile is displayed in one column (or row) and that of the others are displayed in the adjacent columns (or rows), making it easy to create a visual representation that shows how two profiles match. The two extreme columns are called reference ladders and are used, as the name suggests, to provide a way to see interpret the results. A band in the reference ladder refers to a particular length. They usually start at the bottom, so you as you move up the ladder, you would considering sequences of length 2, 3, 4 etc. If the sample has a band that corresponds to the 4 on the reference ladder, it means that the sample has 4 repeats. You could very well represent a DNA profile as numbers in a table, but that doesn’t look as good on T. V. which is why you probably won’ t see it on CSI anytime soon.

And that folks is the story of DNA profiling. So the next time you read a procedural about how DNA was used to solve a crime, sit back, relax, and let all the talk of markers and PCR and nucleotides wash over you because now you know what they mean. Hopefully.

C is for Corpus Delicti/Criminal Procedure

photo credit: bloomsberries via photopin cc

The earth has revolved 7 times and that means that it is time for another edition of the Crime Fiction Alphabet meme. If you are unfamiliar with CFA, it is a challenge run by Kerrie over at Mysteries in Paradise, so head on there and sign up, or click on some links and read what others have to say. This is my second time at this carnival, and I have chosen to focus on topics related to crime fiction rather than books and/or authors. But first, a message:

Disclaimer: I’m not a lawyer and this blog post is not intended in any way to be legal advice. It is merely my understanding of certain legal terms and procedures that may be helpful to the crime fiction writer (or reader).

With that out of the way, let’s move on to this week’s topic – which it so happens, is a twofer

C is for Corpus Delicti/Criminal Procedure

Corpus Delicti (meaning “body of the crime”) is a latin term that signifies the need to establish that a crime has occurred before a person can be convicted of that crime. As Perry Mason was fond of saying in many of his cases involving murder: “Corpus Delicti does not literally mean that there needs to be a body, it just means that there needs to be enough evidence to establish that a crime has been committed.” For example, maybe a witness saw the murder being committed but the victim’s body cannot be found, there is still enough evidence (assuming a reliable witness) to establish that a crime has occurred. Together with Actus Reus (guilty act) and Mens Rea (guilty mind),  Corpus Delicti establishes the important details of prosecuting a criminal act – i.e., there must be a criminal act, the accused’s conduct must have resulted in the crime, and in certain cases, this conduct must have been intentional.

So what happens when a crime is committed and someone is accused?

1. The suspect or suspects are arrested.
2. Once arrested and booked into county jail, the suspect is presented before a magistrate or municipal judge for a preliminary arraignment. At the arraignment, bail is set, and the suspects are advised of their constitutional rights and the charges against them.
3. A preliminary hearing is scheduled in a week to ten days, where a judge establishes that there is a prima facie evidence that a crime has been committed and that there is reasonable grounds to believe that the suspect committed the crime. The suspect enters their plea at this hearing.
4.  In some states (in the United States that is), a Grand Jury convenes to examine the evidence and decide whether the case against the suspect should proceed.
5. Trial, Verdict and Sentencing.
6. If found guilty, Probation or Incarceration .
7. If incarcerated, Parole

That concludes an extremely abridged version of criminal procedure in the United States. Of course, there are any number of variations on this theme, and differences depending on which state you are in. The procedures and steps also vary considerably in another country.

PSA of the week: Jury Nullification.

B is for Blood

photo credit: Jack Spades via photopin cc

It is time to mind your ABCs because it is Crime Fiction Alphabet (CFA) time. If you are unfamiliar with CFA, it is a challenge run by Kerrie over at Mysteries in Paradise, so head on there and sign up, or click on some links and read what others have to say. This is my second time at this rodeo, and I have chosen to focus on topics related to crime fiction rather than books and/or authors. So without further ado,

I hope you had your dinner a while ago because if you don’t like blood, this could get queasy. But, if you’re a vampire, then this is your lucky day. Let’s start by getting the basics out of the way.

First, the etymology. According to the Oxford English Dictionary, the word “blood” dates to the oldest English, circa 1000 AD. The word is derived from Middle English, which is derived from the Old English word blôd, which is akin to the Old High German word bluot, meaning blood. The modern German word is (das) Blut.

Second, the biology. Blood is made up of 4 things – plasma (the liquid part of the blood) and the three kinds of cells – Red Blood Cells (the oxygen carriers), White Blood Cells (the infection fighters and, more importantly for crime fiction writers, where the DNA is found), and Platelets (which allows blood to clot). This is overly simplified and, of course, common knowledge to most of us but is worth repeating.

Now, for the most important part, the use of blood in criminology. In forensic medicine, the term blood residue is used to refer to the wet and dry remnants of blood. But before you can start analyzing blood residue, you have to find it. If you have watched an episode of CSI or any other forensic procedural, or read a book on the same topic, you know about Luminol – that stuff they spray on surfaces to detect blood residue. Luminol reacts to the iron found in hemoglobin and turns blue. The reaction lasts only about 30 seconds but even minute traces of iron is enough to cause the reaction. However, Luminol does have drawbacks – it responds to other compounds like those containing copper and certain bleaches. Cleaning with bleach doesn’t remove blood residue as much as disguise it enough that an accurate reading cannot be made. Horseradish sauce and poop also cause false-positives. Now imagine your murderer, cleaning up after himself by opening up a jar of horseradish sauce or, better still, taking the time to err… do his business, after he has done his business.

Once we have found the blood, it can help us solve crimes! Of course, everyone knows that blood residue gives us DNA (but only the white blood cells do that. Red blood cells do not have nuclei) that can help identify both victims and murderers. But blood can do much more. Properly done, it can tell you when the crime happened and where.

If you have read more than one Perry Mason novel, it is likely you have encountered the use of blood pooling in determining the time of death. When the heart stops beating, blood stops flowing and starts to settle (pool), and depending on a number of factors (like the temperature, body position etc), the settling of blood has a specific timeline that can be used to determine when death occurred  In addition, freshly dried bloodstains are reddish-brown in color. Over time, under sunlight and exposure to weather patterns, blood fades to a gray stain.

The second aspect of blood in forensic evidence is in bloodstain pattern analysis - or that thing that Marg Helgenberger and Michael C. Hall do in CSI and Dexter respectively. Spatter analysis can help the analyst determine where the event happened in 3-dimensional space – i.e., where and how high off the floor the victim was when the blow fell. They can do this because the shape of a stain is an ellipse, and the ratio of the major and minor axes of the ellipse (the width and length of the shape) is equal to the sine of the angle of impact of the droplet. Some trigonometry later, you can determine the angle at which the droplet traveled  If you have enough such droplets, you can construct their paths and find out where they converge. This convergence point is most likely where the event happened. Of course, the details are a little more complicated but the process is straightforward.

Even when the blood is still in the body, it can tell the analyst the state of the victim before he or she died. Bruising indicates areas of trauma that can point us to the cause of death. Analyzing the blood itself can also be helpful. Exposure to Carbon Monoxide causes blood to be bright red. In Cyanide poisoning, body is unable to absorb oxygen leading to increase redness of your venous blood (blood in your veins) .The specific list of blood tests and the poisons that can be detected with them is too long for this blog post but they are out there but hopefully the next time your victim keels over, you know some of the different ways you can make their death interesting and mysterious.

Trivia that may interest only me.

The jumping spider uses blood flow like a hydraulic pump,  forcing its blood into the legs under pressure causing the legs to straighten for a powerful jump, without the need for bulky muscles.

Bloodletting, while mostly a load of crock, can actually be used in the management of a few rare diseases, including Hemochromatosis and Polycythemia. If I remember correctly, there was an episode of House devoted to exactly this (After 8 seasons, I would be surprised if there wasn’t an episode of House devoted to some strange unheard of disease and/or cure).

A is for Alkaloids

Hooray, it is that time of the year when you open up your bookcases (does anyone have bookcases with doors anymore?) and search madly for books and authors that start with A. Yup, it is Crime Fiction Alphabet time. For those not in the know, the Crime Fiction Alphabet is administered (hey I used A) by the wonderful Kerrie over at Mysteries in Paradise, so head on there and sign up, or click on some links and read what others have to say.

This time around, I’m moving away from books and going to try and write about topics related to crime. This week’s highlight is Alkaloids!

To quote Wikipedia, “Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms.” Well Peter, that’s all good you say, but it’s not really crime material. Ah, but wait, there is more! Most alkaloids are poisonous in large enough amount but some are deadly in minute doses. And that is why authors love em!

Take Strychnine for example. It really doesn’t have any other use except as a pesticide. Small amounts (less than half a gram) is enough to kill a human. Death by Strychnine is extremely painful and results in muscle convulsions and asphyxia.

Strychnine not your cup of tea (har har)? Don’t worry, there is morphine, hemlock, belladonna (talk about a misnomer), mescaline, coniine, and on, and on. And there are a variety of ways that detective novels find to deliver this impressive variety of poisons – from the ubiquitous cup of tea, to fish sandwiches, eye drops, berries, nicotine patches, coated straws and many more. The moral, if you are not the detective in a mystery story, is to not touch, smell, eat, or drink anything. To be on the safe side, you should probably not look at anything as well.

P. S. – I considered for a moment that I could use poisons for the entire alphabet but that would be too easy (I’m looking at you Xanthium and Zantedeschia).

P. P. S. – I will now clear my browsing history and really really hope no one in my immediate circle of family and friends gets poisoned.

The Natural Victim cover art

NaNoWriMo update

I signed up for NaNoWriMo last year and though the whole idea conjures up visions of having the first draft of a book in a month, I went into it with a blank slate as far as expectations were concerned. I guess there was a part of me that resisted any idea of churning out a novel in such a short time, and I think that resistance came because of the time I spent writing The Natural Victim.

So how did I do?
Not well.

I started out pretty good. For the first few days, I was hitting my goals but there was this nagging doubt in the back of my head that what I was writing wasn’t very good. I knew that wasn’t the point of NaNoWriMo but it still didn’t sit well with me. Churning out a lot of words wasn’t high on my agenda I guess. I didn’t have writer’s block, just a regular case of writer’s laziness, and the way to get through it was to write my usual quota of 1000 words/day rather than the 1677 words/day that NaNoWriMo required. Besides, I like thinking through my plots as I write and the extra 677 words/day puts a cramp on that thinking because I only write for about an hour every day. In fairness to NaNoWriMo, it did deliver on its promise… I doubled the size of my novel in a week (I had started this one a while ago but put it off to focus on The Natural Victim) but I feel if I hadn’t stopped when I did I would have had to rewrite a large part of it.

I won’t be signing up for NaNoWriMo again but I’m glad I did it once, for two reasons – One, I have a better understanding of how I write, and two,it did help me find the following site –  http://bestofnanowrimo.tumblr.com/.

Brace Yourself…